[libcamera-devel,v2,2/2] pipeline: raspberrypi: Add support for Video Mux and Bridge devices
diff mbox series

Message ID 20211208151527.1404715-3-naush@raspberrypi.com
State Superseded
Headers show
Series
  • Raspberry Pi: Add video mux and bridge support
Related show

Commit Message

Naushir Patuck Dec. 8, 2021, 3:15 p.m. UTC
This change will allow the pipeline handler to enumerate and control Video
Mux or Bridge devices that may be attached between sensors and a particular
Unicam instance. Cascaded mux or bridge devices are also handled.

A new member function enumerateVideoDevices(), called from registerCamera(), is
used to identify and open all mux and bridge subdevices present in the
sensor -> Unicam link.

Relevent links are enabled/disabled and pad formats correctly set in configure()
before the camera is started.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
---
 .../pipeline/raspberrypi/raspberrypi.cpp      | 78 +++++++++++++++++++
 1 file changed, 78 insertions(+)

Comments

Kieran Bingham Dec. 9, 2021, 9:39 a.m. UTC | #1
Quoting Naushir Patuck (2021-12-08 15:15:27)
> This change will allow the pipeline handler to enumerate and control Video
> Mux or Bridge devices that may be attached between sensors and a particular
> Unicam instance. Cascaded mux or bridge devices are also handled.
> 
> A new member function enumerateVideoDevices(), called from registerCamera(), is
> used to identify and open all mux and bridge subdevices present in the
> sensor -> Unicam link.
> 
> Relevent links are enabled/disabled and pad formats correctly set in configure()
> before the camera is started.
> 
> Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> ---
>  .../pipeline/raspberrypi/raspberrypi.cpp      | 78 +++++++++++++++++++
>  1 file changed, 78 insertions(+)
> 
> diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> index 756878c70036..ca176ecb40ec 100644
> --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> @@ -12,6 +12,7 @@
>  #include <mutex>
>  #include <queue>
>  #include <unordered_set>
> +#include <utility>
>  
>  #include <libcamera/base/shared_fd.h>
>  #include <libcamera/base/utils.h>
> @@ -220,6 +221,11 @@ public:
>         std::vector<RPi::Stream *> streams_;
>         /* Stores the ids of the buffers mapped in the IPA. */
>         std::unordered_set<unsigned int> ipaBuffers_;
> +       /*
> +        * Stores a cascade of Video Mux or Bridge devices between the sensor and
> +        * Unicam together with media link across the entities.
> +        */
> +       std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink *>> bridgeDevices_;
>  
>         /* DMAHEAP allocation helper. */
>         RPi::DmaHeap dmaHeap_;
> @@ -311,6 +317,7 @@ private:
>         }
>  
>         int registerCamera(MediaDevice *unicam, MediaDevice *isp, MediaEntity *sensorEntity);
> +       void enumerateVideoDevices(RPiCameraData *data, MediaLink *link);
>         int queueAllBuffers(Camera *camera);
>         int prepareBuffers(Camera *camera);
>         void freeBuffers(Camera *camera);
> @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
>          */
>         data->properties_.set(properties::ScalerCropMaximum, data->sensorInfo_.analogCrop);
>  
> +       /* Setup the Video Mux/Bridge entities. */
> +       for (auto &[device, link] : data->bridgeDevices_) {
> +               /* Start by disabling all the sink pad links on the devices in the cascade. */
> +               for (const MediaPad *p : device->entity()->pads()) {
> +                       if (!(p->flags() & MEDIA_PAD_FL_SINK))
> +                               continue;
> +
> +                       for (MediaLink *l : p->links())
> +                               l->setEnabled(false);
> +               }
> +
> +               /* Finally enable the link, and setup the pad format. */
> +               link->setEnabled(true);

Isn't this going to enable /all/ bridge links in the cascade
incorrectly?


   ┌──────────┐
   │  Unicam  │
   └─────▲────┘
         │
     ┌───┴───┐
     │  Mux  ◄───────┐
     └──▲────┘       │
        │            │
  ┌─────┴───┐    ┌───┴───┐
  │ Sensor1 │    │  Mux  │◄──┐
  └─────────┘    └─▲─────┘   │
                   │         │
           ┌───────┴─┐   ┌───┴─────┐
           │ Sensor2 │   │ Sensor3 │
           └─────────┘   └─────────┘

In that 'use case' we're now iterating over all bridges and enabling
their link, I think which means we've just enabled both muxes,
immediately after disabling them - even for Sensor1?

Maybe I've mis-understood it, but I thought there would be something
that would start at the desired sensor, and walk up the links to the
unicam enabling those links (and only those) as it went up?

The walk only has to be done once too, so perhaps a per-camera(sensor)
vector of links to iterate and enable?

Or maybe I'm missing the separation between the bridgeDevices_ and the
per-camera instances. But if that's already happening, I can't then see
how each camera data clears all the bridges used by other cameras...


> +               const MediaPad *srcPad = link->sink();
> +               ret = device->setFormat(srcPad->index(), &sensorFormat);

This assignment of ret is in a loop, so earlier failures are going to
get ignored, unchecked.

> +               LOG(RPI, Info) << "Configured media link on device " << device->entity()->name()
> +                              << " at pad " << srcPad->index();
> +       }
> +
>         return ret;
>  }
>  
> @@ -1098,6 +1124,13 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
>         if (data->sensor_->init())
>                 return -EINVAL;
>  
> +       /*
> +        * Enumerate all the Video Mux/Bridge devices across the sensor -> unicam
> +        * link. There may be a cascade of devices in this link!
> +        */
> +       MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
> +       enumerateVideoDevices(data.get(), link);
> +
>         data->sensorFormats_ = populateSensorFormats(data->sensor_);
>  
>         ipa::RPi::SensorConfig sensorConfig;
> @@ -1224,6 +1257,51 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
>         return 0;
>  }
>  
> +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data, MediaLink *link)
> +{
> +       const MediaPad *sinkPad = link->sink();
> +       const MediaEntity *entity = sinkPad->entity();
> +       bool unicamFound = false;
> +
> +       /* We only deal with Video Mux and Bridge devices in cascade. */
> +       if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> +           entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> +               return;
> +
> +       LOG(RPI, Info) << "Found video mux device " << entity->name()
> +                      << " linked to sink pad " << sinkPad->index();
> +
> +       data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity), link);
> +       data->bridgeDevices_.back().first->open();

Going through the above, I can't help but wonder if the bridgeDevices_
should be stored as a single instance in the Pipeline handler (not each
CameraData, we have one CameraData per camera right? if so, how does
camera3 disable all the links? does it know about every path?)


> +
> +       for (const MediaPad *pad : entity->pads()) {
> +               /*
> +                * Iterate through all the sink pads down the cascade to find any
> +                * other Video Mux and Bridge devices.
> +                */
> +               if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> +                       continue;
> +
> +               for (MediaLink *l : pad->links()) {
> +                       enumerateVideoDevices(data, l);
> +                       if (l->sink()->entity()->name() == "unicam-image")
> +                               unicamFound = true;
> +               }
> +       }
> +
> +       /* This identifies the end of our entity enumeration recursion. */
> +       if (link->source()->entity()->function() == MEDIA_ENT_F_CAM_SENSOR) {
> +               /*
> +               * If Unicam is not at the end of this cascade, we cannot configure
> +               * this topology automatically, so remove all entity references.
> +               */
> +               if (!unicamFound) {
> +                       LOG(RPI, Warning) << "Cannot automatically configure this MC topology!";
> +                       data->bridgeDevices_.clear();
> +               }
> +       }
> +}
> +
>  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
>  {
>         RPiCameraData *data = cameraData(camera);
> -- 
> 2.25.1
>
Naushir Patuck Dec. 9, 2021, 10:07 a.m. UTC | #2
Hi Kieran,

Thanks for your feedback.

On Thu, 9 Dec 2021 at 09:39, Kieran Bingham <kieran.bingham@ideasonboard.com>
wrote:

> Quoting Naushir Patuck (2021-12-08 15:15:27)
> > This change will allow the pipeline handler to enumerate and control
> Video
> > Mux or Bridge devices that may be attached between sensors and a
> particular
> > Unicam instance. Cascaded mux or bridge devices are also handled.
> >
> > A new member function enumerateVideoDevices(), called from
> registerCamera(), is
> > used to identify and open all mux and bridge subdevices present in the
> > sensor -> Unicam link.
> >
> > Relevent links are enabled/disabled and pad formats correctly set in
> configure()
> > before the camera is started.
> >
> > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > ---
> >  .../pipeline/raspberrypi/raspberrypi.cpp      | 78 +++++++++++++++++++
> >  1 file changed, 78 insertions(+)
> >
> > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > index 756878c70036..ca176ecb40ec 100644
> > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > @@ -12,6 +12,7 @@
> >  #include <mutex>
> >  #include <queue>
> >  #include <unordered_set>
> > +#include <utility>
> >
> >  #include <libcamera/base/shared_fd.h>
> >  #include <libcamera/base/utils.h>
> > @@ -220,6 +221,11 @@ public:
> >         std::vector<RPi::Stream *> streams_;
> >         /* Stores the ids of the buffers mapped in the IPA. */
> >         std::unordered_set<unsigned int> ipaBuffers_;
> > +       /*
> > +        * Stores a cascade of Video Mux or Bridge devices between the
> sensor and
> > +        * Unicam together with media link across the entities.
> > +        */
> > +       std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink
> *>> bridgeDevices_;
> >
> >         /* DMAHEAP allocation helper. */
> >         RPi::DmaHeap dmaHeap_;
> > @@ -311,6 +317,7 @@ private:
> >         }
> >
> >         int registerCamera(MediaDevice *unicam, MediaDevice *isp,
> MediaEntity *sensorEntity);
> > +       void enumerateVideoDevices(RPiCameraData *data, MediaLink *link);
> >         int queueAllBuffers(Camera *camera);
> >         int prepareBuffers(Camera *camera);
> >         void freeBuffers(Camera *camera);
> > @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera *camera,
> CameraConfiguration *config)
> >          */
> >         data->properties_.set(properties::ScalerCropMaximum,
> data->sensorInfo_.analogCrop);
> >
> > +       /* Setup the Video Mux/Bridge entities. */
> > +       for (auto &[device, link] : data->bridgeDevices_) {
> > +               /* Start by disabling all the sink pad links on the
> devices in the cascade. */
> > +               for (const MediaPad *p : device->entity()->pads()) {
> > +                       if (!(p->flags() & MEDIA_PAD_FL_SINK))
> > +                               continue;
> > +
> > +                       for (MediaLink *l : p->links())
> > +                               l->setEnabled(false);
> > +               }
> > +
> > +               /* Finally enable the link, and setup the pad format. */
> > +               link->setEnabled(true);
>
> Isn't this going to enable /all/ bridge links in the cascade
> incorrectly?
>
>
>    ┌──────────┐
>    │  Unicam  │
>    └─────▲────┘
>          │
>      ┌───┴───┐
>      │  Mux  ◄───────┐
>      └──▲────┘       │
>         │            │
>   ┌─────┴───┐    ┌───┴───┐
>   │ Sensor1 │    │  Mux  │◄──┐
>   └─────────┘    └─▲─────┘   │
>                    │         │
>            ┌───────┴─┐   ┌───┴─────┐
>            │ Sensor2 │   │ Sensor3 │
>            └─────────┘   └─────────┘
>
> In that 'use case' we're now iterating over all bridges and enabling
> their link, I think which means we've just enabled both muxes,
> immediately after disabling them - even for Sensor1?
>
> Maybe I've mis-understood it, but I thought there would be something
> that would start at the desired sensor, and walk up the links to the
> unicam enabling those links (and only those) as it went up?
>
> The walk only has to be done once too, so perhaps a per-camera(sensor)
> vector of links to iterate and enable?
>
> Or maybe I'm missing the separation between the bridgeDevices_ and the
> per-camera instances. But if that's already happening, I can't then see
> how each camera data clears all the bridges used by other cameras...
>

Let me explain my intention, and you can then tell me if the code does
what I think it does :-)

Each sensor (Sensor{1,2,3}) will register its own Camera object, and
in that object bridgeDevices_ will store the cascade of muxes between
the sensor and the Unicam port. So, for Sensor1, we store only 1 mux,
and Sensor{2,3} will store both muxes. Together with the mux device,
we also store the entity to entity links.

The above code goes through those stored entities, first disabling *all*
links on each device in the chain, and then selectively enabling
the specific links that are stored in bridgeDevices_ to link sensor
to Unicam across all intermedia muxes.  If Sensor1 is used, this
does mean that the Sensor{2,3} -> Mux links might not change
state but the Mux to Mux link will be disabled.  Similarly, if we are
driving
Sensor3, the  Sensor{1,2} -> Mux link will be disabled.


>
> > +               const MediaPad *srcPad = link->sink();
> > +               ret = device->setFormat(srcPad->index(), &sensorFormat);
>
> This assignment of ret is in a loop, so earlier failures are going to
> get ignored, unchecked.
>

This should not matter, as ret is only used in the loop to count successful
camera registrations.  The return value from match() will be false only if
0 cameras were registered.


>
> > +               LOG(RPI, Info) << "Configured media link on device " <<
> device->entity()->name()
> > +                              << " at pad " << srcPad->index();
> > +       }
> > +
> >         return ret;
> >  }
> >
> > @@ -1098,6 +1124,13 @@ int
> PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> >         if (data->sensor_->init())
> >                 return -EINVAL;
> >
> > +       /*
> > +        * Enumerate all the Video Mux/Bridge devices across the sensor
> -> unicam
> > +        * link. There may be a cascade of devices in this link!
> > +        */
> > +       MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
> > +       enumerateVideoDevices(data.get(), link);
> > +
> >         data->sensorFormats_ = populateSensorFormats(data->sensor_);
> >
> >         ipa::RPi::SensorConfig sensorConfig;
> > @@ -1224,6 +1257,51 @@ int
> PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> >         return 0;
> >  }
> >
> > +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data,
> MediaLink *link)
> > +{
> > +       const MediaPad *sinkPad = link->sink();
> > +       const MediaEntity *entity = sinkPad->entity();
> > +       bool unicamFound = false;
> > +
> > +       /* We only deal with Video Mux and Bridge devices in cascade. */
> > +       if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> > +           entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> > +               return;
> > +
> > +       LOG(RPI, Info) << "Found video mux device " << entity->name()
> > +                      << " linked to sink pad " << sinkPad->index();
> > +
> > +
>  data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),
> link);
> > +       data->bridgeDevices_.back().first->open();
>
> Going through the above, I can't help but wonder if the bridgeDevices_
> should be stored as a single instance in the Pipeline handler (not each
> CameraData, we have one CameraData per camera right? if so, how does
> camera3 disable all the links? does it know about every path?)
>

From my description earlier, bridgeDevices_ must be stored in the
CameraData, as
it lists the devices in the path between the sensor and Unicam.  And this
is unique
per-sensor.  Again, this does mean that if we are using Sensor1, links for
Sensor{2,3}
-> Mux are not changed, but the Mux->Mux link will be disabled.  Do you
think
that may not be appropriate leaving them enabled?

Please shout if this doesn't make sense, and something simpler might
equally work :-)

Cheers,
Naush



>
>
> > +
> > +       for (const MediaPad *pad : entity->pads()) {
> > +               /*
> > +                * Iterate through all the sink pads down the cascade to
> find any
> > +                * other Video Mux and Bridge devices.
> > +                */
> > +               if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> > +                       continue;
> > +
> > +               for (MediaLink *l : pad->links()) {
> > +                       enumerateVideoDevices(data, l);
> > +                       if (l->sink()->entity()->name() ==
> "unicam-image")
> > +                               unicamFound = true;
> > +               }
> > +       }
> > +
> > +       /* This identifies the end of our entity enumeration recursion.
> */
> > +       if (link->source()->entity()->function() ==
> MEDIA_ENT_F_CAM_SENSOR) {
> > +               /*
> > +               * If Unicam is not at the end of this cascade, we cannot
> configure
> > +               * this topology automatically, so remove all entity
> references.
> > +               */
> > +               if (!unicamFound) {
> > +                       LOG(RPI, Warning) << "Cannot automatically
> configure this MC topology!";
> > +                       data->bridgeDevices_.clear();
> > +               }
> > +       }
> > +}
> > +
> >  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> >  {
> >         RPiCameraData *data = cameraData(camera);
> > --
> > 2.25.1
> >
>
Kieran Bingham Dec. 9, 2021, 10:25 a.m. UTC | #3
Quoting Naushir Patuck (2021-12-09 10:07:43)
> Hi Kieran,
> 
> Thanks for your feedback.
> 
> On Thu, 9 Dec 2021 at 09:39, Kieran Bingham <kieran.bingham@ideasonboard.com>
> wrote:
> 
> > Quoting Naushir Patuck (2021-12-08 15:15:27)
> > > This change will allow the pipeline handler to enumerate and control
> > Video
> > > Mux or Bridge devices that may be attached between sensors and a
> > particular
> > > Unicam instance. Cascaded mux or bridge devices are also handled.
> > >
> > > A new member function enumerateVideoDevices(), called from
> > registerCamera(), is
> > > used to identify and open all mux and bridge subdevices present in the
> > > sensor -> Unicam link.
> > >
> > > Relevent links are enabled/disabled and pad formats correctly set in
> > configure()
> > > before the camera is started.
> > >
> > > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > > ---
> > >  .../pipeline/raspberrypi/raspberrypi.cpp      | 78 +++++++++++++++++++
> > >  1 file changed, 78 insertions(+)
> > >
> > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > index 756878c70036..ca176ecb40ec 100644
> > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > @@ -12,6 +12,7 @@
> > >  #include <mutex>
> > >  #include <queue>
> > >  #include <unordered_set>
> > > +#include <utility>
> > >
> > >  #include <libcamera/base/shared_fd.h>
> > >  #include <libcamera/base/utils.h>
> > > @@ -220,6 +221,11 @@ public:
> > >         std::vector<RPi::Stream *> streams_;
> > >         /* Stores the ids of the buffers mapped in the IPA. */
> > >         std::unordered_set<unsigned int> ipaBuffers_;
> > > +       /*
> > > +        * Stores a cascade of Video Mux or Bridge devices between the
> > sensor and
> > > +        * Unicam together with media link across the entities.
> > > +        */
> > > +       std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink
> > *>> bridgeDevices_;
> > >
> > >         /* DMAHEAP allocation helper. */
> > >         RPi::DmaHeap dmaHeap_;
> > > @@ -311,6 +317,7 @@ private:
> > >         }
> > >
> > >         int registerCamera(MediaDevice *unicam, MediaDevice *isp,
> > MediaEntity *sensorEntity);
> > > +       void enumerateVideoDevices(RPiCameraData *data, MediaLink *link);
> > >         int queueAllBuffers(Camera *camera);
> > >         int prepareBuffers(Camera *camera);
> > >         void freeBuffers(Camera *camera);
> > > @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera *camera,
> > CameraConfiguration *config)
> > >          */
> > >         data->properties_.set(properties::ScalerCropMaximum,
> > data->sensorInfo_.analogCrop);
> > >
> > > +       /* Setup the Video Mux/Bridge entities. */
> > > +       for (auto &[device, link] : data->bridgeDevices_) {
> > > +               /* Start by disabling all the sink pad links on the
> > devices in the cascade. */
> > > +               for (const MediaPad *p : device->entity()->pads()) {
> > > +                       if (!(p->flags() & MEDIA_PAD_FL_SINK))
> > > +                               continue;
> > > +
> > > +                       for (MediaLink *l : p->links())
> > > +                               l->setEnabled(false);
> > > +               }
> > > +
> > > +               /* Finally enable the link, and setup the pad format. */
> > > +               link->setEnabled(true);
> >
> > Isn't this going to enable /all/ bridge links in the cascade
> > incorrectly?
> >
> >
> >    ┌──────────┐
> >    │  Unicam  │
> >    └─────▲────┘
> >          │
> >      ┌───┴───┐
> >      │  Mux  ◄───────┐
> >      └──▲────┘       │
> >         │            │
> >   ┌─────┴───┐    ┌───┴───┐
> >   │ Sensor1 │    │  Mux  │◄──┐
> >   └─────────┘    └─▲─────┘   │
> >                    │         │
> >            ┌───────┴─┐   ┌───┴─────┐
> >            │ Sensor2 │   │ Sensor3 │
> >            └─────────┘   └─────────┘
> >
> > In that 'use case' we're now iterating over all bridges and enabling
> > their link, I think which means we've just enabled both muxes,
> > immediately after disabling them - even for Sensor1?
> >
> > Maybe I've mis-understood it, but I thought there would be something
> > that would start at the desired sensor, and walk up the links to the
> > unicam enabling those links (and only those) as it went up?
> >
> > The walk only has to be done once too, so perhaps a per-camera(sensor)
> > vector of links to iterate and enable?
> >
> > Or maybe I'm missing the separation between the bridgeDevices_ and the
> > per-camera instances. But if that's already happening, I can't then see
> > how each camera data clears all the bridges used by other cameras...
> >
> 
> Let me explain my intention, and you can then tell me if the code does
> what I think it does :-)
> 
> Each sensor (Sensor{1,2,3}) will register its own Camera object, and
> in that object bridgeDevices_ will store the cascade of muxes between
> the sensor and the Unicam port. So, for Sensor1, we store only 1 mux,
> and Sensor{2,3} will store both muxes. Together with the mux device,
> we also store the entity to entity links.
> 
> The above code goes through those stored entities, first disabling *all*
> links on each device in the chain, and then selectively enabling
> the specific links that are stored in bridgeDevices_ to link sensor
> to Unicam across all intermedia muxes.  If Sensor1 is used, this
> does mean that the Sensor{2,3} -> Mux links might not change
> state but the Mux to Mux link will be disabled.  Similarly, if we are
> driving
> Sensor3, the  Sensor{1,2} -> Mux link will be disabled.

I think I see the obvious part I missed ;-)

It doesn't matter what configuration Mux2 has as long as Mux1 only has
Sensor1 link enabled!

It might help to document that in the comments somehow somewhere?
Particularly now that you've already written the explanation to me -
perhaps it should be a block comment above enumerateVideoDevices.

Feel free to take or add the ascii diagram, I think more pictures in
our documentation are always helpful. It's really easy to make those
block diagrams in ascii art at https://asciiflow.com.


> >
> > > +               const MediaPad *srcPad = link->sink();
> > > +               ret = device->setFormat(srcPad->index(), &sensorFormat);
> >
> > This assignment of ret is in a loop, so earlier failures are going to
> > get ignored, unchecked.
> >
> 
> This should not matter, as ret is only used in the loop to count successful
> camera registrations.  The return value from match() will be false only if
> 0 cameras were registered.

So should we not even assign it?
Do we need to report a warning if it failed to set the format?

But aren't we here in configure() setting the format of the device to
propogate the format?

If we fail to setFormat in that case, then I think we should be saying
the configure() call failed?



> 
> 
> >
> > > +               LOG(RPI, Info) << "Configured media link on device " <<
> > device->entity()->name()
> > > +                              << " at pad " << srcPad->index();
> > > +       }
> > > +
> > >         return ret;
> > >  }
> > >
> > > @@ -1098,6 +1124,13 @@ int
> > PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > >         if (data->sensor_->init())
> > >                 return -EINVAL;
> > >
> > > +       /*
> > > +        * Enumerate all the Video Mux/Bridge devices across the sensor
> > -> unicam
> > > +        * link. There may be a cascade of devices in this link!
> > > +        */
> > > +       MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
> > > +       enumerateVideoDevices(data.get(), link);
> > > +
> > >         data->sensorFormats_ = populateSensorFormats(data->sensor_);
> > >
> > >         ipa::RPi::SensorConfig sensorConfig;
> > > @@ -1224,6 +1257,51 @@ int
> > PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > >         return 0;
> > >  }
> > >
> > > +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data,
> > MediaLink *link)
> > > +{
> > > +       const MediaPad *sinkPad = link->sink();
> > > +       const MediaEntity *entity = sinkPad->entity();
> > > +       bool unicamFound = false;
> > > +
> > > +       /* We only deal with Video Mux and Bridge devices in cascade. */
> > > +       if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> > > +           entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> > > +               return;
> > > +
> > > +       LOG(RPI, Info) << "Found video mux device " << entity->name()
> > > +                      << " linked to sink pad " << sinkPad->index();
> > > +
> > > +
> >  data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),
> > link);
> > > +       data->bridgeDevices_.back().first->open();
> >
> > Going through the above, I can't help but wonder if the bridgeDevices_
> > should be stored as a single instance in the Pipeline handler (not each
> > CameraData, we have one CameraData per camera right? if so, how does
> > camera3 disable all the links? does it know about every path?)
> >
> 
> From my description earlier, bridgeDevices_ must be stored in the
> CameraData, as
> it lists the devices in the path between the sensor and Unicam.  And this
> is unique
> per-sensor.  Again, this does mean that if we are using Sensor1, links for
> Sensor{2,3}
> -> Mux are not changed, but the Mux->Mux link will be disabled.  Do you
> think
> that may not be appropriate leaving them enabled?

I missed that, and now it's obvious. If the first mux is only pointing
to Sensor1, then indeed it doesn't matter what mux2 is configured to
link to...

So I think that's ok.

> 
> Please shout if this doesn't make sense, and something simpler might
> equally work :-)

It's all fine until someone adds a crossbar perhaps that might make it
possible to do more crazy things ;-)

But we don't need to worry about that now I dont' think.

I think I'm still concerned about that ret during the loop in
configure(). But with that resolved:

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

> Cheers,
> Naush
> 
> 
> 
> >
> >
> > > +
> > > +       for (const MediaPad *pad : entity->pads()) {
> > > +               /*
> > > +                * Iterate through all the sink pads down the cascade to
> > find any
> > > +                * other Video Mux and Bridge devices.
> > > +                */
> > > +               if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> > > +                       continue;
> > > +
> > > +               for (MediaLink *l : pad->links()) {
> > > +                       enumerateVideoDevices(data, l);
> > > +                       if (l->sink()->entity()->name() ==
> > "unicam-image")
> > > +                               unicamFound = true;
> > > +               }
> > > +       }
> > > +
> > > +       /* This identifies the end of our entity enumeration recursion.
> > */
> > > +       if (link->source()->entity()->function() ==
> > MEDIA_ENT_F_CAM_SENSOR) {
> > > +               /*
> > > +               * If Unicam is not at the end of this cascade, we cannot
> > configure
> > > +               * this topology automatically, so remove all entity
> > references.
> > > +               */
> > > +               if (!unicamFound) {
> > > +                       LOG(RPI, Warning) << "Cannot automatically
> > configure this MC topology!";
> > > +                       data->bridgeDevices_.clear();
> > > +               }
> > > +       }
> > > +}
> > > +
> > >  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> > >  {
> > >         RPiCameraData *data = cameraData(camera);
> > > --
> > > 2.25.1
> > >
> >
Naushir Patuck Dec. 9, 2021, 10:29 a.m. UTC | #4
Hi Kieran,

On Thu, 9 Dec 2021 at 10:25, Kieran Bingham <kieran.bingham@ideasonboard.com>
wrote:

> Quoting Naushir Patuck (2021-12-09 10:07:43)
> > Hi Kieran,
> >
> > Thanks for your feedback.
> >
> > On Thu, 9 Dec 2021 at 09:39, Kieran Bingham <
> kieran.bingham@ideasonboard.com>
> > wrote:
> >
> > > Quoting Naushir Patuck (2021-12-08 15:15:27)
> > > > This change will allow the pipeline handler to enumerate and control
> > > Video
> > > > Mux or Bridge devices that may be attached between sensors and a
> > > particular
> > > > Unicam instance. Cascaded mux or bridge devices are also handled.
> > > >
> > > > A new member function enumerateVideoDevices(), called from
> > > registerCamera(), is
> > > > used to identify and open all mux and bridge subdevices present in
> the
> > > > sensor -> Unicam link.
> > > >
> > > > Relevent links are enabled/disabled and pad formats correctly set in
> > > configure()
> > > > before the camera is started.
> > > >
> > > > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > > > ---
> > > >  .../pipeline/raspberrypi/raspberrypi.cpp      | 78
> +++++++++++++++++++
> > > >  1 file changed, 78 insertions(+)
> > > >
> > > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > index 756878c70036..ca176ecb40ec 100644
> > > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > @@ -12,6 +12,7 @@
> > > >  #include <mutex>
> > > >  #include <queue>
> > > >  #include <unordered_set>
> > > > +#include <utility>
> > > >
> > > >  #include <libcamera/base/shared_fd.h>
> > > >  #include <libcamera/base/utils.h>
> > > > @@ -220,6 +221,11 @@ public:
> > > >         std::vector<RPi::Stream *> streams_;
> > > >         /* Stores the ids of the buffers mapped in the IPA. */
> > > >         std::unordered_set<unsigned int> ipaBuffers_;
> > > > +       /*
> > > > +        * Stores a cascade of Video Mux or Bridge devices between
> the
> > > sensor and
> > > > +        * Unicam together with media link across the entities.
> > > > +        */
> > > > +       std::vector<std::pair<std::unique_ptr<V4L2Subdevice>,
> MediaLink
> > > *>> bridgeDevices_;
> > > >
> > > >         /* DMAHEAP allocation helper. */
> > > >         RPi::DmaHeap dmaHeap_;
> > > > @@ -311,6 +317,7 @@ private:
> > > >         }
> > > >
> > > >         int registerCamera(MediaDevice *unicam, MediaDevice *isp,
> > > MediaEntity *sensorEntity);
> > > > +       void enumerateVideoDevices(RPiCameraData *data, MediaLink
> *link);
> > > >         int queueAllBuffers(Camera *camera);
> > > >         int prepareBuffers(Camera *camera);
> > > >         void freeBuffers(Camera *camera);
> > > > @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera
> *camera,
> > > CameraConfiguration *config)
> > > >          */
> > > >         data->properties_.set(properties::ScalerCropMaximum,
> > > data->sensorInfo_.analogCrop);
> > > >
> > > > +       /* Setup the Video Mux/Bridge entities. */
> > > > +       for (auto &[device, link] : data->bridgeDevices_) {
> > > > +               /* Start by disabling all the sink pad links on the
> > > devices in the cascade. */
> > > > +               for (const MediaPad *p : device->entity()->pads()) {
> > > > +                       if (!(p->flags() & MEDIA_PAD_FL_SINK))
> > > > +                               continue;
> > > > +
> > > > +                       for (MediaLink *l : p->links())
> > > > +                               l->setEnabled(false);
> > > > +               }
> > > > +
> > > > +               /* Finally enable the link, and setup the pad
> format. */
> > > > +               link->setEnabled(true);
> > >
> > > Isn't this going to enable /all/ bridge links in the cascade
> > > incorrectly?
> > >
> > >
> > >    ┌──────────┐
> > >    │  Unicam  │
> > >    └─────▲────┘
> > >          │
> > >      ┌───┴───┐
> > >      │  Mux  ◄───────┐
> > >      └──▲────┘       │
> > >         │            │
> > >   ┌─────┴───┐    ┌───┴───┐
> > >   │ Sensor1 │    │  Mux  │◄──┐
> > >   └─────────┘    └─▲─────┘   │
> > >                    │         │
> > >            ┌───────┴─┐   ┌───┴─────┐
> > >            │ Sensor2 │   │ Sensor3 │
> > >            └─────────┘   └─────────┘
> > >
> > > In that 'use case' we're now iterating over all bridges and enabling
> > > their link, I think which means we've just enabled both muxes,
> > > immediately after disabling them - even for Sensor1?
> > >
> > > Maybe I've mis-understood it, but I thought there would be something
> > > that would start at the desired sensor, and walk up the links to the
> > > unicam enabling those links (and only those) as it went up?
> > >
> > > The walk only has to be done once too, so perhaps a per-camera(sensor)
> > > vector of links to iterate and enable?
> > >
> > > Or maybe I'm missing the separation between the bridgeDevices_ and the
> > > per-camera instances. But if that's already happening, I can't then see
> > > how each camera data clears all the bridges used by other cameras...
> > >
> >
> > Let me explain my intention, and you can then tell me if the code does
> > what I think it does :-)
> >
> > Each sensor (Sensor{1,2,3}) will register its own Camera object, and
> > in that object bridgeDevices_ will store the cascade of muxes between
> > the sensor and the Unicam port. So, for Sensor1, we store only 1 mux,
> > and Sensor{2,3} will store both muxes. Together with the mux device,
> > we also store the entity to entity links.
> >
> > The above code goes through those stored entities, first disabling *all*
> > links on each device in the chain, and then selectively enabling
> > the specific links that are stored in bridgeDevices_ to link sensor
> > to Unicam across all intermedia muxes.  If Sensor1 is used, this
> > does mean that the Sensor{2,3} -> Mux links might not change
> > state but the Mux to Mux link will be disabled.  Similarly, if we are
> > driving
> > Sensor3, the  Sensor{1,2} -> Mux link will be disabled.
>
> I think I see the obvious part I missed ;-)
>
> It doesn't matter what configuration Mux2 has as long as Mux1 only has
> Sensor1 link enabled!
>
> It might help to document that in the comments somehow somewhere?
> Particularly now that you've already written the explanation to me -
> perhaps it should be a block comment above enumerateVideoDevices.
>
> Feel free to take or add the ascii diagram, I think more pictures in
> our documentation are always helpful. It's really easy to make those
> block diagrams in ascii art at https://asciiflow.com.
>

Sure, I'll add some comments through the code explaining it in more detail.


>
>
> > >
> > > > +               const MediaPad *srcPad = link->sink();
> > > > +               ret = device->setFormat(srcPad->index(),
> &sensorFormat);
> > >
> > > This assignment of ret is in a loop, so earlier failures are going to
> > > get ignored, unchecked.
> > >
> >
> > This should not matter, as ret is only used in the loop to count
> successful
> > camera registrations.  The return value from match() will be false only
> if
> > 0 cameras were registered.
>
> So should we not even assign it?
> Do we need to report a warning if it failed to set the format?
>
> But aren't we here in configure() setting the format of the device to
> propogate the format?
>
> If we fail to setFormat in that case, then I think we should be saying
> the configure() call failed?
>

Oops, my mistake.  I misread your original comment and what bit of
code it refers to!  This ret value *is* used for the return path, and must
be accounted for correctly as it is set in a loop! I'll fix this in the next
revision.


>
>
>
> >
> >
> > >
> > > > +               LOG(RPI, Info) << "Configured media link on device "
> <<
> > > device->entity()->name()
> > > > +                              << " at pad " << srcPad->index();
> > > > +       }
> > > > +
> > > >         return ret;
> > > >  }
> > > >
> > > > @@ -1098,6 +1124,13 @@ int
> > > PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice
> *isp, Me
> > > >         if (data->sensor_->init())
> > > >                 return -EINVAL;
> > > >
> > > > +       /*
> > > > +        * Enumerate all the Video Mux/Bridge devices across the
> sensor
> > > -> unicam
> > > > +        * link. There may be a cascade of devices in this link!
> > > > +        */
> > > > +       MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
> > > > +       enumerateVideoDevices(data.get(), link);
> > > > +
> > > >         data->sensorFormats_ = populateSensorFormats(data->sensor_);
> > > >
> > > >         ipa::RPi::SensorConfig sensorConfig;
> > > > @@ -1224,6 +1257,51 @@ int
> > > PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice
> *isp, Me
> > > >         return 0;
> > > >  }
> > > >
> > > > +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data,
> > > MediaLink *link)
> > > > +{
> > > > +       const MediaPad *sinkPad = link->sink();
> > > > +       const MediaEntity *entity = sinkPad->entity();
> > > > +       bool unicamFound = false;
> > > > +
> > > > +       /* We only deal with Video Mux and Bridge devices in
> cascade. */
> > > > +       if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> > > > +           entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> > > > +               return;
> > > > +
> > > > +       LOG(RPI, Info) << "Found video mux device " << entity->name()
> > > > +                      << " linked to sink pad " << sinkPad->index();
> > > > +
> > > > +
> > >
> data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),
> > > link);
> > > > +       data->bridgeDevices_.back().first->open();
> > >
> > > Going through the above, I can't help but wonder if the bridgeDevices_
> > > should be stored as a single instance in the Pipeline handler (not each
> > > CameraData, we have one CameraData per camera right? if so, how does
> > > camera3 disable all the links? does it know about every path?)
> > >
> >
> > From my description earlier, bridgeDevices_ must be stored in the
> > CameraData, as
> > it lists the devices in the path between the sensor and Unicam.  And this
> > is unique
> > per-sensor.  Again, this does mean that if we are using Sensor1, links
> for
> > Sensor{2,3}
> > -> Mux are not changed, but the Mux->Mux link will be disabled.  Do you
> > think
> > that may not be appropriate leaving them enabled?
>
> I missed that, and now it's obvious. If the first mux is only pointing
> to Sensor1, then indeed it doesn't matter what mux2 is configured to
> link to...
>
> So I think that's ok.
>
> >
> > Please shout if this doesn't make sense, and something simpler might
> > equally work :-)
>
> It's all fine until someone adds a crossbar perhaps that might make it
> possible to do more crazy things ;-)
>
> But we don't need to worry about that now I dont' think.
>
> I think I'm still concerned about that ret during the loop in
> configure(). But with that resolved:
>
> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
>
> > Cheers,
> > Naush
> >
> >
> >
> > >
> > >
> > > > +
> > > > +       for (const MediaPad *pad : entity->pads()) {
> > > > +               /*
> > > > +                * Iterate through all the sink pads down the
> cascade to
> > > find any
> > > > +                * other Video Mux and Bridge devices.
> > > > +                */
> > > > +               if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> > > > +                       continue;
> > > > +
> > > > +               for (MediaLink *l : pad->links()) {
> > > > +                       enumerateVideoDevices(data, l);
> > > > +                       if (l->sink()->entity()->name() ==
> > > "unicam-image")
> > > > +                               unicamFound = true;
> > > > +               }
> > > > +       }
> > > > +
> > > > +       /* This identifies the end of our entity enumeration
> recursion.
> > > */
> > > > +       if (link->source()->entity()->function() ==
> > > MEDIA_ENT_F_CAM_SENSOR) {
> > > > +               /*
> > > > +               * If Unicam is not at the end of this cascade, we
> cannot
> > > configure
> > > > +               * this topology automatically, so remove all entity
> > > references.
> > > > +               */
> > > > +               if (!unicamFound) {
> > > > +                       LOG(RPI, Warning) << "Cannot automatically
> > > configure this MC topology!";
> > > > +                       data->bridgeDevices_.clear();
> > > > +               }
> > > > +       }
> > > > +}
> > > > +
> > > >  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> > > >  {
> > > >         RPiCameraData *data = cameraData(camera);
> > > > --
> > > > 2.25.1
> > > >
> > >
>
Laurent Pinchart Dec. 10, 2021, 12:24 a.m. UTC | #5
Hi Naush,

On Thu, Dec 09, 2021 at 10:29:21AM +0000, Naushir Patuck wrote:
> On Thu, 9 Dec 2021 at 10:25, Kieran Bingham wrote:
> > Quoting Naushir Patuck (2021-12-09 10:07:43)
> > > On Thu, 9 Dec 2021 at 09:39, Kieran Bingham wrote:
> > > > Quoting Naushir Patuck (2021-12-08 15:15:27)
> > > > > This change will allow the pipeline handler to enumerate and control Video
> > > > > Mux or Bridge devices that may be attached between sensors and a particular
> > > > > Unicam instance. Cascaded mux or bridge devices are also handled.
> > > > >
> > > > > A new member function enumerateVideoDevices(), called from registerCamera(), is
> > > > > used to identify and open all mux and bridge subdevices present in the
> > > > > sensor -> Unicam link.
> > > > >
> > > > > Relevent links are enabled/disabled and pad formats correctly set in configure()
> > > > > before the camera is started.
> > > > >
> > > > > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > > > > ---
> > > > >  .../pipeline/raspberrypi/raspberrypi.cpp      | 78 +++++++++++++++++++
> > > > >  1 file changed, 78 insertions(+)
> > > > >
> > > > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > index 756878c70036..ca176ecb40ec 100644
> > > > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > @@ -12,6 +12,7 @@
> > > > >  #include <mutex>
> > > > >  #include <queue>
> > > > >  #include <unordered_set>
> > > > > +#include <utility>
> > > > >
> > > > >  #include <libcamera/base/shared_fd.h>
> > > > >  #include <libcamera/base/utils.h>
> > > > > @@ -220,6 +221,11 @@ public:
> > > > >         std::vector<RPi::Stream *> streams_;
> > > > >         /* Stores the ids of the buffers mapped in the IPA. */
> > > > >         std::unordered_set<unsigned int> ipaBuffers_;
> > > > > +       /*
> > > > > +        * Stores a cascade of Video Mux or Bridge devices between the sensor and
> > > > > +        * Unicam together with media link across the entities.
> > > > > +        */
> > > > > +       std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink *>> bridgeDevices_;
> > > > >
> > > > >         /* DMAHEAP allocation helper. */
> > > > >         RPi::DmaHeap dmaHeap_;
> > > > > @@ -311,6 +317,7 @@ private:
> > > > >         }
> > > > >
> > > > >         int registerCamera(MediaDevice *unicam, MediaDevice *isp, MediaEntity *sensorEntity);
> > > > > +       void enumerateVideoDevices(RPiCameraData *data, MediaLink *link);
> > > > >         int queueAllBuffers(Camera *camera);
> > > > >         int prepareBuffers(Camera *camera);
> > > > >         void freeBuffers(Camera *camera);
> > > > > @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
> > > > >          */
> > > > >         data->properties_.set(properties::ScalerCropMaximum, data->sensorInfo_.analogCrop);
> > > > >
> > > > > +       /* Setup the Video Mux/Bridge entities. */
> > > > > +       for (auto &[device, link] : data->bridgeDevices_) {
> > > > > +               /* Start by disabling all the sink pad links on the devices in the cascade. */
> > > > > +               for (const MediaPad *p : device->entity()->pads()) {
> > > > > +                       if (!(p->flags() & MEDIA_PAD_FL_SINK))
> > > > > +                               continue;
> > > > > +
> > > > > +                       for (MediaLink *l : p->links())
> > > > > +                               l->setEnabled(false);

As an optimization, you could skip disabling the link that you will
enable below.

> > > > > +               }
> > > > > +
> > > > > +               /* Finally enable the link, and setup the pad format. */
> > > > > +               link->setEnabled(true);
> > > >
> > > > Isn't this going to enable /all/ bridge links in the cascade
> > > > incorrectly?
> > > >
> > > >
> > > >    ┌──────────┐
> > > >    │  Unicam  │
> > > >    └─────▲────┘
> > > >          │
> > > >      ┌───┴───┐
> > > >      │  Mux  ◄───────┐
> > > >      └──▲────┘       │
> > > >         │            │
> > > >   ┌─────┴───┐    ┌───┴───┐
> > > >   │ Sensor1 │    │  Mux  │◄──┐
> > > >   └─────────┘    └─▲─────┘   │
> > > >                    │         │
> > > >            ┌───────┴─┐   ┌───┴─────┐
> > > >            │ Sensor2 │   │ Sensor3 │
> > > >            └─────────┘   └─────────┘
> > > >
> > > > In that 'use case' we're now iterating over all bridges and enabling
> > > > their link, I think which means we've just enabled both muxes,
> > > > immediately after disabling them - even for Sensor1?
> > > >
> > > > Maybe I've mis-understood it, but I thought there would be something
> > > > that would start at the desired sensor, and walk up the links to the
> > > > unicam enabling those links (and only those) as it went up?
> > > >
> > > > The walk only has to be done once too, so perhaps a per-camera(sensor)
> > > > vector of links to iterate and enable?
> > > >
> > > > Or maybe I'm missing the separation between the bridgeDevices_ and the
> > > > per-camera instances. But if that's already happening, I can't then see
> > > > how each camera data clears all the bridges used by other cameras...
> > >
> > > Let me explain my intention, and you can then tell me if the code does
> > > what I think it does :-)
> > >
> > > Each sensor (Sensor{1,2,3}) will register its own Camera object, and
> > > in that object bridgeDevices_ will store the cascade of muxes between
> > > the sensor and the Unicam port. So, for Sensor1, we store only 1 mux,
> > > and Sensor{2,3} will store both muxes. Together with the mux device,
> > > we also store the entity to entity links.
> > >
> > > The above code goes through those stored entities, first disabling *all*
> > > links on each device in the chain, and then selectively enabling
> > > the specific links that are stored in bridgeDevices_ to link sensor
> > > to Unicam across all intermedia muxes.  If Sensor1 is used, this
> > > does mean that the Sensor{2,3} -> Mux links might not change
> > > state but the Mux to Mux link will be disabled.  Similarly, if we are driving
> > > Sensor3, the  Sensor{1,2} -> Mux link will be disabled.
> >
> > I think I see the obvious part I missed ;-)
> >
> > It doesn't matter what configuration Mux2 has as long as Mux1 only has
> > Sensor1 link enabled!
> >
> > It might help to document that in the comments somehow somewhere?
> > Particularly now that you've already written the explanation to me -
> > perhaps it should be a block comment above enumerateVideoDevices.
> >
> > Feel free to take or add the ascii diagram, I think more pictures in
> > our documentation are always helpful. It's really easy to make those
> > block diagrams in ascii art at https://asciiflow.com.
> 
> Sure, I'll add some comments through the code explaining it in more detail.
> 
> > > > > +               const MediaPad *srcPad = link->sink();
> > > > > +               ret = device->setFormat(srcPad->index(), &sensorFormat);
> > > >
> > > > This assignment of ret is in a loop, so earlier failures are going to
> > > > get ignored, unchecked.
> > >
> > > This should not matter, as ret is only used in the loop to count successful
> > > camera registrations.  The return value from match() will be false only if
> > > 0 cameras were registered.
> >
> > So should we not even assign it?
> > Do we need to report a warning if it failed to set the format?
> >
> > But aren't we here in configure() setting the format of the device to
> > propogate the format?
> >
> > If we fail to setFormat in that case, then I think we should be saying
> > the configure() call failed?
> 
> Oops, my mistake.  I misread your original comment and what bit of
> code it refers to!  This ret value *is* used for the return path, and must
> be accounted for correctly as it is set in a loop! I'll fix this in the next
> revision.
> 
> > > > > +               LOG(RPI, Info) << "Configured media link on device " << device->entity()->name()
> > > > > +                              << " at pad " << srcPad->index();
> > > > > +       }
> > > > > +
> > > > >         return ret;
> > > > >  }
> > > > >
> > > > > @@ -1098,6 +1124,13 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > > > >         if (data->sensor_->init())
> > > > >                 return -EINVAL;
> > > > >
> > > > > +       /*
> > > > > +        * Enumerate all the Video Mux/Bridge devices across the sensor -> unicam
> > > > > +        * link. There may be a cascade of devices in this link!
> > > > > +        */
> > > > > +       MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
> > > > > +       enumerateVideoDevices(data.get(), link);
> > > > > +
> > > > >         data->sensorFormats_ = populateSensorFormats(data->sensor_);
> > > > >
> > > > >         ipa::RPi::SensorConfig sensorConfig;
> > > > > @@ -1224,6 +1257,51 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > > > >         return 0;
> > > > >  }
> > > > >
> > > > > +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data, MediaLink *link)

This function accesses members of data but doesn't seem to access any
member of PipelineHandlerRPi. Could it be moved to RPiCameraData ?

> > > > > +{
> > > > > +       const MediaPad *sinkPad = link->sink();
> > > > > +       const MediaEntity *entity = sinkPad->entity();
> > > > > +       bool unicamFound = false;
> > > > > +
> > > > > +       /* We only deal with Video Mux and Bridge devices in cascade. */
> > > > > +       if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> > > > > +           entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> > > > > +               return;
> > > > > +
> > > > > +       LOG(RPI, Info) << "Found video mux device " << entity->name()
> > > > > +                      << " linked to sink pad " << sinkPad->index();
> > > > > +
> > > > > +       data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),link);
> > > > > +       data->bridgeDevices_.back().first->open();
> > > >
> > > > Going through the above, I can't help but wonder if the bridgeDevices_
> > > > should be stored as a single instance in the Pipeline handler (not each
> > > > CameraData, we have one CameraData per camera right? if so, how does
> > > > camera3 disable all the links? does it know about every path?)
> > >
> > > From my description earlier, bridgeDevices_ must be stored in the CameraData, as
> > > it lists the devices in the path between the sensor and Unicam.  And this is unique
> > > per-sensor.  Again, this does mean that if we are using Sensor1, links for Sensor{2,3}
> > > -> Mux are not changed, but the Mux->Mux link will be disabled.  Do you think
> > > that may not be appropriate leaving them enabled?

I can't help but seeing lots of similarities with the simple pipeline
handler, which also performs dynamic discovery of pipelines (all the way
to the video node in that case, while in your case it would be all the
way to the Unicam device). I wonder if we could share code between the
two ? This could benefit the Raspberry Pi pipeline handler by providing
a more generic version of format propagation through the pipeline
(although that part may be more difficult to share).

An important difference between the two implementations is that the
simple pipeline handler opens the video node and subdevs once only,
storing them in the pipeline handler instance, and only stores pointers
to those objects in the camera data.

> > I missed that, and now it's obvious. If the first mux is only pointing
> > to Sensor1, then indeed it doesn't matter what mux2 is configured to
> > link to...
> >
> > So I think that's ok.
> >
> > > Please shout if this doesn't make sense, and something simpler might
> > > equally work :-)
> >
> > It's all fine until someone adds a crossbar perhaps that might make it
> > possible to do more crazy things ;-)
> >
> > But we don't need to worry about that now I dont' think.
> >
> > I think I'm still concerned about that ret during the loop in
> > configure(). But with that resolved:
> >
> > Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> >
> > > > > +
> > > > > +       for (const MediaPad *pad : entity->pads()) {
> > > > > +               /*
> > > > > +                * Iterate through all the sink pads down the cascade to find any
> > > > > +                * other Video Mux and Bridge devices.
> > > > > +                */
> > > > > +               if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> > > > > +                       continue;
> > > > > +
> > > > > +               for (MediaLink *l : pad->links()) {
> > > > > +                       enumerateVideoDevices(data, l);
> > > > > +                       if (l->sink()->entity()->name() == "unicam-image")
> > > > > +                               unicamFound = true;
> > > > > +               }
> > > > > +       }
> > > > > +
> > > > > +       /* This identifies the end of our entity enumeration recursion. */
> > > > > +       if (link->source()->entity()->function() == MEDIA_ENT_F_CAM_SENSOR) {
> > > > > +               /*
> > > > > +               * If Unicam is not at the end of this cascade, we cannot configure
> > > > > +               * this topology automatically, so remove all entity references.
> > > > > +               */
> > > > > +               if (!unicamFound) {
> > > > > +                       LOG(RPI, Warning) << "Cannot automatically configure this MC topology!";
> > > > > +                       data->bridgeDevices_.clear();
> > > > > +               }
> > > > > +       }
> > > > > +}
> > > > > +
> > > > >  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> > > > >  {
> > > > >         RPiCameraData *data = cameraData(camera);
Naushir Patuck Dec. 10, 2021, 3:48 p.m. UTC | #6
Hi Laurent,

Thank you for your feedback.

On Fri, 10 Dec 2021 at 00:24, Laurent Pinchart <
laurent.pinchart@ideasonboard.com> wrote:

> Hi Naush,
>
> On Thu, Dec 09, 2021 at 10:29:21AM +0000, Naushir Patuck wrote:
> > On Thu, 9 Dec 2021 at 10:25, Kieran Bingham wrote:
> > > Quoting Naushir Patuck (2021-12-09 10:07:43)
> > > > On Thu, 9 Dec 2021 at 09:39, Kieran Bingham wrote:
> > > > > Quoting Naushir Patuck (2021-12-08 15:15:27)
> > > > > > This change will allow the pipeline handler to enumerate and
> control Video
> > > > > > Mux or Bridge devices that may be attached between sensors and a
> particular
> > > > > > Unicam instance. Cascaded mux or bridge devices are also handled.
> > > > > >
> > > > > > A new member function enumerateVideoDevices(), called from
> registerCamera(), is
> > > > > > used to identify and open all mux and bridge subdevices present
> in the
> > > > > > sensor -> Unicam link.
> > > > > >
> > > > > > Relevent links are enabled/disabled and pad formats correctly
> set in configure()
> > > > > > before the camera is started.
> > > > > >
> > > > > > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > > > > > ---
> > > > > >  .../pipeline/raspberrypi/raspberrypi.cpp      | 78
> +++++++++++++++++++
> > > > > >  1 file changed, 78 insertions(+)
> > > > > >
> > > > > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > index 756878c70036..ca176ecb40ec 100644
> > > > > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > @@ -12,6 +12,7 @@
> > > > > >  #include <mutex>
> > > > > >  #include <queue>
> > > > > >  #include <unordered_set>
> > > > > > +#include <utility>
> > > > > >
> > > > > >  #include <libcamera/base/shared_fd.h>
> > > > > >  #include <libcamera/base/utils.h>
> > > > > > @@ -220,6 +221,11 @@ public:
> > > > > >         std::vector<RPi::Stream *> streams_;
> > > > > >         /* Stores the ids of the buffers mapped in the IPA. */
> > > > > >         std::unordered_set<unsigned int> ipaBuffers_;
> > > > > > +       /*
> > > > > > +        * Stores a cascade of Video Mux or Bridge devices
> between the sensor and
> > > > > > +        * Unicam together with media link across the entities.
> > > > > > +        */
> > > > > > +       std::vector<std::pair<std::unique_ptr<V4L2Subdevice>,
> MediaLink *>> bridgeDevices_;
> > > > > >
> > > > > >         /* DMAHEAP allocation helper. */
> > > > > >         RPi::DmaHeap dmaHeap_;
> > > > > > @@ -311,6 +317,7 @@ private:
> > > > > >         }
> > > > > >
> > > > > >         int registerCamera(MediaDevice *unicam, MediaDevice
> *isp, MediaEntity *sensorEntity);
> > > > > > +       void enumerateVideoDevices(RPiCameraData *data,
> MediaLink *link);
> > > > > >         int queueAllBuffers(Camera *camera);
> > > > > >         int prepareBuffers(Camera *camera);
> > > > > >         void freeBuffers(Camera *camera);
> > > > > > @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera
> *camera, CameraConfiguration *config)
> > > > > >          */
> > > > > >         data->properties_.set(properties::ScalerCropMaximum,
> data->sensorInfo_.analogCrop);
> > > > > >
> > > > > > +       /* Setup the Video Mux/Bridge entities. */
> > > > > > +       for (auto &[device, link] : data->bridgeDevices_) {
> > > > > > +               /* Start by disabling all the sink pad links on
> the devices in the cascade. */
> > > > > > +               for (const MediaPad *p :
> device->entity()->pads()) {
> > > > > > +                       if (!(p->flags() & MEDIA_PAD_FL_SINK))
> > > > > > +                               continue;
> > > > > > +
> > > > > > +                       for (MediaLink *l : p->links())
> > > > > > +                               l->setEnabled(false);
>
> As an optimization, you could skip disabling the link that you will
> enable below.
>

Ack.


>
> > > > > > +               }
> > > > > > +
> > > > > > +               /* Finally enable the link, and setup the pad
> format. */
> > > > > > +               link->setEnabled(true);
> > > > >
> > > > > Isn't this going to enable /all/ bridge links in the cascade
> > > > > incorrectly?
> > > > >
> > > > >
> > > > >    ┌──────────┐
> > > > >    │  Unicam  │
> > > > >    └─────▲────┘
> > > > >          │
> > > > >      ┌───┴───┐
> > > > >      │  Mux  ◄───────┐
> > > > >      └──▲────┘       │
> > > > >         │            │
> > > > >   ┌─────┴───┐    ┌───┴───┐
> > > > >   │ Sensor1 │    │  Mux  │◄──┐
> > > > >   └─────────┘    └─▲─────┘   │
> > > > >                    │         │
> > > > >            ┌───────┴─┐   ┌───┴─────┐
> > > > >            │ Sensor2 │   │ Sensor3 │
> > > > >            └─────────┘   └─────────┘
> > > > >
> > > > > In that 'use case' we're now iterating over all bridges and
> enabling
> > > > > their link, I think which means we've just enabled both muxes,
> > > > > immediately after disabling them - even for Sensor1?
> > > > >
> > > > > Maybe I've mis-understood it, but I thought there would be
> something
> > > > > that would start at the desired sensor, and walk up the links to
> the
> > > > > unicam enabling those links (and only those) as it went up?
> > > > >
> > > > > The walk only has to be done once too, so perhaps a
> per-camera(sensor)
> > > > > vector of links to iterate and enable?
> > > > >
> > > > > Or maybe I'm missing the separation between the bridgeDevices_ and
> the
> > > > > per-camera instances. But if that's already happening, I can't
> then see
> > > > > how each camera data clears all the bridges used by other
> cameras...
> > > >
> > > > Let me explain my intention, and you can then tell me if the code
> does
> > > > what I think it does :-)
> > > >
> > > > Each sensor (Sensor{1,2,3}) will register its own Camera object, and
> > > > in that object bridgeDevices_ will store the cascade of muxes between
> > > > the sensor and the Unicam port. So, for Sensor1, we store only 1 mux,
> > > > and Sensor{2,3} will store both muxes. Together with the mux device,
> > > > we also store the entity to entity links.
> > > >
> > > > The above code goes through those stored entities, first disabling
> *all*
> > > > links on each device in the chain, and then selectively enabling
> > > > the specific links that are stored in bridgeDevices_ to link sensor
> > > > to Unicam across all intermedia muxes.  If Sensor1 is used, this
> > > > does mean that the Sensor{2,3} -> Mux links might not change
> > > > state but the Mux to Mux link will be disabled.  Similarly, if we
> are driving
> > > > Sensor3, the  Sensor{1,2} -> Mux link will be disabled.
> > >
> > > I think I see the obvious part I missed ;-)
> > >
> > > It doesn't matter what configuration Mux2 has as long as Mux1 only has
> > > Sensor1 link enabled!
> > >
> > > It might help to document that in the comments somehow somewhere?
> > > Particularly now that you've already written the explanation to me -
> > > perhaps it should be a block comment above enumerateVideoDevices.
> > >
> > > Feel free to take or add the ascii diagram, I think more pictures in
> > > our documentation are always helpful. It's really easy to make those
> > > block diagrams in ascii art at https://asciiflow.com.
> >
> > Sure, I'll add some comments through the code explaining it in more
> detail.
> >
> > > > > > +               const MediaPad *srcPad = link->sink();
> > > > > > +               ret = device->setFormat(srcPad->index(),
> &sensorFormat);
> > > > >
> > > > > This assignment of ret is in a loop, so earlier failures are going
> to
> > > > > get ignored, unchecked.
> > > >
> > > > This should not matter, as ret is only used in the loop to count
> successful
> > > > camera registrations.  The return value from match() will be false
> only if
> > > > 0 cameras were registered.
> > >
> > > So should we not even assign it?
> > > Do we need to report a warning if it failed to set the format?
> > >
> > > But aren't we here in configure() setting the format of the device to
> > > propogate the format?
> > >
> > > If we fail to setFormat in that case, then I think we should be saying
> > > the configure() call failed?
> >
> > Oops, my mistake.  I misread your original comment and what bit of
> > code it refers to!  This ret value *is* used for the return path, and
> must
> > be accounted for correctly as it is set in a loop! I'll fix this in the
> next
> > revision.
> >
> > > > > > +               LOG(RPI, Info) << "Configured media link on
> device " << device->entity()->name()
> > > > > > +                              << " at pad " << srcPad->index();
> > > > > > +       }
> > > > > > +
> > > > > >         return ret;
> > > > > >  }
> > > > > >
> > > > > > @@ -1098,6 +1124,13 @@ int
> PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > > > > >         if (data->sensor_->init())
> > > > > >                 return -EINVAL;
> > > > > >
> > > > > > +       /*
> > > > > > +        * Enumerate all the Video Mux/Bridge devices across the
> sensor -> unicam
> > > > > > +        * link. There may be a cascade of devices in this link!
> > > > > > +        */
> > > > > > +       MediaLink *link =
> sensorEntity->getPadByIndex(0)->links()[0];
> > > > > > +       enumerateVideoDevices(data.get(), link);
> > > > > > +
> > > > > >         data->sensorFormats_ =
> populateSensorFormats(data->sensor_);
> > > > > >
> > > > > >         ipa::RPi::SensorConfig sensorConfig;
> > > > > > @@ -1224,6 +1257,51 @@ int
> PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > > > > >         return 0;
> > > > > >  }
> > > > > >
> > > > > > +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData
> *data, MediaLink *link)
>
> This function accesses members of data but doesn't seem to access any
> member of PipelineHandlerRPi. Could it be moved to RPiCameraData ?
>

Yes, I can do that.


>
> > > > > > +{
> > > > > > +       const MediaPad *sinkPad = link->sink();
> > > > > > +       const MediaEntity *entity = sinkPad->entity();
> > > > > > +       bool unicamFound = false;
> > > > > > +
> > > > > > +       /* We only deal with Video Mux and Bridge devices in
> cascade. */
> > > > > > +       if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> > > > > > +           entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> > > > > > +               return;
> > > > > > +
> > > > > > +       LOG(RPI, Info) << "Found video mux device " <<
> entity->name()
> > > > > > +                      << " linked to sink pad " <<
> sinkPad->index();
> > > > > > +
> > > > > > +
>  data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),link);
> > > > > > +       data->bridgeDevices_.back().first->open();
> > > > >
> > > > > Going through the above, I can't help but wonder if the
> bridgeDevices_
> > > > > should be stored as a single instance in the Pipeline handler (not
> each
> > > > > CameraData, we have one CameraData per camera right? if so, how
> does
> > > > > camera3 disable all the links? does it know about every path?)
> > > >
> > > > From my description earlier, bridgeDevices_ must be stored in the
> CameraData, as
> > > > it lists the devices in the path between the sensor and Unicam.  And
> this is unique
> > > > per-sensor.  Again, this does mean that if we are using Sensor1,
> links for Sensor{2,3}
> > > > -> Mux are not changed, but the Mux->Mux link will be disabled.  Do
> you think
> > > > that may not be appropriate leaving them enabled?
>
> I can't help but seeing lots of similarities with the simple pipeline
> handler, which also performs dynamic discovery of pipelines (all the way
> to the video node in that case, while in your case it would be all the
> way to the Unicam device). I wonder if we could share code between the
> two ? This could benefit the Raspberry Pi pipeline handler by providing
> a more generic version of format propagation through the pipeline
> (although that part may be more difficult to share).
>
> An important difference between the two implementations is that the
> simple pipeline handler opens the video node and subdevs once only,
> storing them in the pipeline handler instance, and only stores pointers
> to those objects in the camera data.
>

I've had a very brief look at the simple pipeline handler.  I agree, there
are
similarities between the two.  I see that the enumeration/discovery in the
simple pipeline handler is a fair bit more sophisticated in finding all
available
entities, whereas the RPi case, I only care to look for a cascade of mux
or bridge devices.

What were your thoughts on trying to share functionality between these two
(and indeed all) pipeline handlers?  Perhaps one way would be to have some
common code to create the media graph structure for any given media device?
This could include entities, pads and links represented in a common way for
pipeline handlers to use?  Then the RPi enumeration code would simply look
to find the devices it cares about. This is probably a bigger job than is
required
for this change though.

Regards,
Naush


> > > I missed that, and now it's obvious. If the first mux is only pointing
> > > to Sensor1, then indeed it doesn't matter what mux2 is configured to
> > > link to...
> > >
> > > So I think that's ok.
> > >
> > > > Please shout if this doesn't make sense, and something simpler might
> > > > equally work :-)
> > >
> > > It's all fine until someone adds a crossbar perhaps that might make it
> > > possible to do more crazy things ;-)
> > >
> > > But we don't need to worry about that now I dont' think.
> > >
> > > I think I'm still concerned about that ret during the loop in
> > > configure(). But with that resolved:
> > >
> > > Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> > >
> > > > > > +
> > > > > > +       for (const MediaPad *pad : entity->pads()) {
> > > > > > +               /*
> > > > > > +                * Iterate through all the sink pads down the
> cascade to find any
> > > > > > +                * other Video Mux and Bridge devices.
> > > > > > +                */
> > > > > > +               if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> > > > > > +                       continue;
> > > > > > +
> > > > > > +               for (MediaLink *l : pad->links()) {
> > > > > > +                       enumerateVideoDevices(data, l);
> > > > > > +                       if (l->sink()->entity()->name() ==
> "unicam-image")
> > > > > > +                               unicamFound = true;
> > > > > > +               }
> > > > > > +       }
> > > > > > +
> > > > > > +       /* This identifies the end of our entity enumeration
> recursion. */
> > > > > > +       if (link->source()->entity()->function() ==
> MEDIA_ENT_F_CAM_SENSOR) {
> > > > > > +               /*
> > > > > > +               * If Unicam is not at the end of this cascade,
> we cannot configure
> > > > > > +               * this topology automatically, so remove all
> entity references.
> > > > > > +               */
> > > > > > +               if (!unicamFound) {
> > > > > > +                       LOG(RPI, Warning) << "Cannot
> automatically configure this MC topology!";
> > > > > > +                       data->bridgeDevices_.clear();
> > > > > > +               }
> > > > > > +       }
> > > > > > +}
> > > > > > +
> > > > > >  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> > > > > >  {
> > > > > >         RPiCameraData *data = cameraData(camera);
>
> --
> Regards,
>
> Laurent Pinchart
>
Laurent Pinchart Dec. 10, 2021, 11:23 p.m. UTC | #7
Hi Naush,

On Fri, Dec 10, 2021 at 03:48:19PM +0000, Naushir Patuck wrote:
> On Fri, 10 Dec 2021 at 00:24, Laurent Pinchart wrote:
> > On Thu, Dec 09, 2021 at 10:29:21AM +0000, Naushir Patuck wrote:
> > > On Thu, 9 Dec 2021 at 10:25, Kieran Bingham wrote:
> > > > Quoting Naushir Patuck (2021-12-09 10:07:43)
> > > > > On Thu, 9 Dec 2021 at 09:39, Kieran Bingham wrote:
> > > > > > Quoting Naushir Patuck (2021-12-08 15:15:27)
> > > > > > > This change will allow the pipeline handler to enumerate and control Video
> > > > > > > Mux or Bridge devices that may be attached between sensors and a particular
> > > > > > > Unicam instance. Cascaded mux or bridge devices are also handled.
> > > > > > >
> > > > > > > A new member function enumerateVideoDevices(), called from registerCamera(), is
> > > > > > > used to identify and open all mux and bridge subdevices present in the
> > > > > > > sensor -> Unicam link.
> > > > > > >
> > > > > > > Relevent links are enabled/disabled and pad formats correctly set in configure()
> > > > > > > before the camera is started.
> > > > > > >
> > > > > > > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > > > > > > ---
> > > > > > >  .../pipeline/raspberrypi/raspberrypi.cpp      | 78 +++++++++++++++++++
> > > > > > >  1 file changed, 78 insertions(+)
> > > > > > >
> > > > > > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > > index 756878c70036..ca176ecb40ec 100644
> > > > > > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > > @@ -12,6 +12,7 @@
> > > > > > >  #include <mutex>
> > > > > > >  #include <queue>
> > > > > > >  #include <unordered_set>
> > > > > > > +#include <utility>
> > > > > > >
> > > > > > >  #include <libcamera/base/shared_fd.h>
> > > > > > >  #include <libcamera/base/utils.h>
> > > > > > > @@ -220,6 +221,11 @@ public:
> > > > > > >         std::vector<RPi::Stream *> streams_;
> > > > > > >         /* Stores the ids of the buffers mapped in the IPA. */
> > > > > > >         std::unordered_set<unsigned int> ipaBuffers_;
> > > > > > > +       /*
> > > > > > > +        * Stores a cascade of Video Mux or Bridge devices between the sensor and
> > > > > > > +        * Unicam together with media link across the entities.
> > > > > > > +        */
> > > > > > > +       std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink *>> bridgeDevices_;
> > > > > > >
> > > > > > >         /* DMAHEAP allocation helper. */
> > > > > > >         RPi::DmaHeap dmaHeap_;
> > > > > > > @@ -311,6 +317,7 @@ private:
> > > > > > >         }
> > > > > > >
> > > > > > >         int registerCamera(MediaDevice *unicam, MediaDevice *isp, MediaEntity *sensorEntity);
> > > > > > > +       void enumerateVideoDevices(RPiCameraData *data, MediaLink *link);
> > > > > > >         int queueAllBuffers(Camera *camera);
> > > > > > >         int prepareBuffers(Camera *camera);
> > > > > > >         void freeBuffers(Camera *camera);
> > > > > > > @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
> > > > > > >          */
> > > > > > >         data->properties_.set(properties::ScalerCropMaximum, data->sensorInfo_.analogCrop);
> > > > > > >
> > > > > > > +       /* Setup the Video Mux/Bridge entities. */
> > > > > > > +       for (auto &[device, link] : data->bridgeDevices_) {
> > > > > > > +               /* Start by disabling all the sink pad links on the devices in the cascade. */
> > > > > > > +               for (const MediaPad *p : device->entity()->pads()) {
> > > > > > > +                       if (!(p->flags() & MEDIA_PAD_FL_SINK))
> > > > > > > +                               continue;
> > > > > > > +
> > > > > > > +                       for (MediaLink *l : p->links())
> > > > > > > +                               l->setEnabled(false);
> >
> > As an optimization, you could skip disabling the link that you will
> > enable below.
> 
> Ack.
> 
> > > > > > > +               }
> > > > > > > +
> > > > > > > +               /* Finally enable the link, and setup the pad format. */
> > > > > > > +               link->setEnabled(true);
> > > > > >
> > > > > > Isn't this going to enable /all/ bridge links in the cascade
> > > > > > incorrectly?
> > > > > >
> > > > > >
> > > > > >    ┌──────────┐
> > > > > >    │  Unicam  │
> > > > > >    └─────▲────┘
> > > > > >          │
> > > > > >      ┌───┴───┐
> > > > > >      │  Mux  ◄───────┐
> > > > > >      └──▲────┘       │
> > > > > >         │            │
> > > > > >   ┌─────┴───┐    ┌───┴───┐
> > > > > >   │ Sensor1 │    │  Mux  │◄──┐
> > > > > >   └─────────┘    └─▲─────┘   │
> > > > > >                    │         │
> > > > > >            ┌───────┴─┐   ┌───┴─────┐
> > > > > >            │ Sensor2 │   │ Sensor3 │
> > > > > >            └─────────┘   └─────────┘
> > > > > >
> > > > > > In that 'use case' we're now iterating over all bridges and enabling
> > > > > > their link, I think which means we've just enabled both muxes,
> > > > > > immediately after disabling them - even for Sensor1?
> > > > > >
> > > > > > Maybe I've mis-understood it, but I thought there would be something
> > > > > > that would start at the desired sensor, and walk up the links to the
> > > > > > unicam enabling those links (and only those) as it went up?
> > > > > >
> > > > > > The walk only has to be done once too, so perhaps a per-camera(sensor)
> > > > > > vector of links to iterate and enable?
> > > > > >
> > > > > > Or maybe I'm missing the separation between the bridgeDevices_ and the
> > > > > > per-camera instances. But if that's already happening, I can't then see
> > > > > > how each camera data clears all the bridges used by other cameras...
> > > > >
> > > > > Let me explain my intention, and you can then tell me if the code does
> > > > > what I think it does :-)
> > > > >
> > > > > Each sensor (Sensor{1,2,3}) will register its own Camera object, and
> > > > > in that object bridgeDevices_ will store the cascade of muxes between
> > > > > the sensor and the Unicam port. So, for Sensor1, we store only 1 mux,
> > > > > and Sensor{2,3} will store both muxes. Together with the mux device,
> > > > > we also store the entity to entity links.
> > > > >
> > > > > The above code goes through those stored entities, first disabling *all*
> > > > > links on each device in the chain, and then selectively enabling
> > > > > the specific links that are stored in bridgeDevices_ to link sensor
> > > > > to Unicam across all intermedia muxes.  If Sensor1 is used, this
> > > > > does mean that the Sensor{2,3} -> Mux links might not change
> > > > > state but the Mux to Mux link will be disabled.  Similarly, if we are driving
> > > > > Sensor3, the  Sensor{1,2} -> Mux link will be disabled.
> > > >
> > > > I think I see the obvious part I missed ;-)
> > > >
> > > > It doesn't matter what configuration Mux2 has as long as Mux1 only has
> > > > Sensor1 link enabled!
> > > >
> > > > It might help to document that in the comments somehow somewhere?
> > > > Particularly now that you've already written the explanation to me -
> > > > perhaps it should be a block comment above enumerateVideoDevices.
> > > >
> > > > Feel free to take or add the ascii diagram, I think more pictures in
> > > > our documentation are always helpful. It's really easy to make those
> > > > block diagrams in ascii art at https://asciiflow.com.
> > >
> > > Sure, I'll add some comments through the code explaining it in more detail.
> > >
> > > > > > > +               const MediaPad *srcPad = link->sink();
> > > > > > > +               ret = device->setFormat(srcPad->index(), &sensorFormat);
> > > > > >
> > > > > > This assignment of ret is in a loop, so earlier failures are going to
> > > > > > get ignored, unchecked.
> > > > >
> > > > > This should not matter, as ret is only used in the loop to count successful
> > > > > camera registrations.  The return value from match() will be false only if
> > > > > 0 cameras were registered.
> > > >
> > > > So should we not even assign it?
> > > > Do we need to report a warning if it failed to set the format?
> > > >
> > > > But aren't we here in configure() setting the format of the device to
> > > > propogate the format?
> > > >
> > > > If we fail to setFormat in that case, then I think we should be saying
> > > > the configure() call failed?
> > >
> > > Oops, my mistake.  I misread your original comment and what bit of
> > > code it refers to!  This ret value *is* used for the return path, and must
> > > be accounted for correctly as it is set in a loop! I'll fix this in the next
> > > revision.
> > >
> > > > > > > +               LOG(RPI, Info) << "Configured media link on device " << device->entity()->name()
> > > > > > > +                              << " at pad " << srcPad->index();
> > > > > > > +       }
> > > > > > > +
> > > > > > >         return ret;
> > > > > > >  }
> > > > > > >
> > > > > > > @@ -1098,6 +1124,13 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > > > > > >         if (data->sensor_->init())
> > > > > > >                 return -EINVAL;
> > > > > > >
> > > > > > > +       /*
> > > > > > > +        * Enumerate all the Video Mux/Bridge devices across the sensor -> unicam
> > > > > > > +        * link. There may be a cascade of devices in this link!
> > > > > > > +        */
> > > > > > > +       MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
> > > > > > > +       enumerateVideoDevices(data.get(), link);
> > > > > > > +
> > > > > > >         data->sensorFormats_ = populateSensorFormats(data->sensor_);
> > > > > > >
> > > > > > >         ipa::RPi::SensorConfig sensorConfig;
> > > > > > > @@ -1224,6 +1257,51 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > > > > > >         return 0;
> > > > > > >  }
> > > > > > >
> > > > > > > +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data, MediaLink *link)
> >
> > This function accesses members of data but doesn't seem to access any
> > member of PipelineHandlerRPi. Could it be moved to RPiCameraData ?
> 
> Yes, I can do that.
> 
> > > > > > > +{
> > > > > > > +       const MediaPad *sinkPad = link->sink();
> > > > > > > +       const MediaEntity *entity = sinkPad->entity();
> > > > > > > +       bool unicamFound = false;
> > > > > > > +
> > > > > > > +       /* We only deal with Video Mux and Bridge devices in cascade. */
> > > > > > > +       if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> > > > > > > +           entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> > > > > > > +               return;
> > > > > > > +
> > > > > > > +       LOG(RPI, Info) << "Found video mux device " << entity->name()
> > > > > > > +                      << " linked to sink pad " << sinkPad->index();
> > > > > > > +
> > > > > > > +  data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),link);
> > > > > > > +       data->bridgeDevices_.back().first->open();
> > > > > >
> > > > > > Going through the above, I can't help but wonder if the bridgeDevices_
> > > > > > should be stored as a single instance in the Pipeline handler (not each
> > > > > > CameraData, we have one CameraData per camera right? if so, how does
> > > > > > camera3 disable all the links? does it know about every path?)
> > > > >
> > > > > From my description earlier, bridgeDevices_ must be stored in the CameraData, as
> > > > > it lists the devices in the path between the sensor and Unicam.  And this is unique
> > > > > per-sensor.  Again, this does mean that if we are using Sensor1, links for Sensor{2,3}
> > > > > -> Mux are not changed, but the Mux->Mux link will be disabled.  Do you think
> > > > > that may not be appropriate leaving them enabled?
> >
> > I can't help but seeing lots of similarities with the simple pipeline
> > handler, which also performs dynamic discovery of pipelines (all the way
> > to the video node in that case, while in your case it would be all the
> > way to the Unicam device). I wonder if we could share code between the
> > two ? This could benefit the Raspberry Pi pipeline handler by providing
> > a more generic version of format propagation through the pipeline
> > (although that part may be more difficult to share).
> >
> > An important difference between the two implementations is that the
> > simple pipeline handler opens the video node and subdevs once only,
> > storing them in the pipeline handler instance, and only stores pointers
> > to those objects in the camera data.
> 
> I've had a very brief look at the simple pipeline handler.  I agree, there are
> similarities between the two.  I see that the enumeration/discovery in the
> simple pipeline handler is a fair bit more sophisticated in finding all available
> entities, whereas the RPi case, I only care to look for a cascade of mux
> or bridge devices.
> 
> What were your thoughts on trying to share functionality between these two
> (and indeed all) pipeline handlers?  Perhaps one way would be to have some
> common code to create the media graph structure for any given media device?
> This could include entities, pads and links represented in a common way for
> pipeline handlers to use?  Then the RPi enumeration code would simply look
> to find the devices it cares about. This is probably a bigger job than is required
> for this change though.

That's a very good question :-)

I don't usually believe in designing helpers without at least a couple
of use cases for them, that more often than not leads to bad designs.
Now we have two examples of code that needs to parse a media graph, and
I expect the exact same feature could be implemented by all pipeline
handlers.

Following the design-from-use-cases philosophy, I think we should focus
on the need at hand. I think it would be able to share code that parses
a media graph to locate sensors and paths from them all the way up to a
given entity (Unicam in your case, any video node in the simple pipeline
handler case), and store the paths in a shared data structure. Functions
to then setup the links in the pipeline seem to also be good candidates
for a common helper.

Format configuration along the pipeline could also possibly be shared,
but that seems more difficult, as the needs appear to be a bit
different.

I do agree this is a bit of yak shaving, as it's not strictly required
to get this feature implemented, but we also have a growing technical
debt. I was thus wondering if you think you could have time to
experiment a little bit.

> > > > I missed that, and now it's obvious. If the first mux is only pointing
> > > > to Sensor1, then indeed it doesn't matter what mux2 is configured to
> > > > link to...
> > > >
> > > > So I think that's ok.
> > > >
> > > > > Please shout if this doesn't make sense, and something simpler might
> > > > > equally work :-)
> > > >
> > > > It's all fine until someone adds a crossbar perhaps that might make it
> > > > possible to do more crazy things ;-)
> > > >
> > > > But we don't need to worry about that now I dont' think.
> > > >
> > > > I think I'm still concerned about that ret during the loop in
> > > > configure(). But with that resolved:
> > > >
> > > > Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> > > >
> > > > > > > +
> > > > > > > +       for (const MediaPad *pad : entity->pads()) {
> > > > > > > +               /*
> > > > > > > +                * Iterate through all the sink pads down the cascade to find any
> > > > > > > +                * other Video Mux and Bridge devices.
> > > > > > > +                */
> > > > > > > +               if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> > > > > > > +                       continue;
> > > > > > > +
> > > > > > > +               for (MediaLink *l : pad->links()) {
> > > > > > > +                       enumerateVideoDevices(data, l);
> > > > > > > +                       if (l->sink()->entity()->name() == "unicam-image")
> > > > > > > +                               unicamFound = true;
> > > > > > > +               }
> > > > > > > +       }
> > > > > > > +
> > > > > > > +       /* This identifies the end of our entity enumeration recursion. */
> > > > > > > +       if (link->source()->entity()->function() == MEDIA_ENT_F_CAM_SENSOR) {
> > > > > > > +               /*
> > > > > > > +               * If Unicam is not at the end of this cascade, we cannot configure
> > > > > > > +               * this topology automatically, so remove all entity references.
> > > > > > > +               */
> > > > > > > +               if (!unicamFound) {
> > > > > > > +                       LOG(RPI, Warning) << "Cannot automatically configure this MC topology!";
> > > > > > > +                       data->bridgeDevices_.clear();
> > > > > > > +               }
> > > > > > > +       }
> > > > > > > +}
> > > > > > > +
> > > > > > >  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> > > > > > >  {
> > > > > > >         RPiCameraData *data = cameraData(camera);
Naushir Patuck Dec. 14, 2021, 8:29 a.m. UTC | #8
Hi Laurent,

On Fri, 10 Dec 2021 at 23:24, Laurent Pinchart <
laurent.pinchart@ideasonboard.com> wrote:

> Hi Naush,
>
> On Fri, Dec 10, 2021 at 03:48:19PM +0000, Naushir Patuck wrote:
> > On Fri, 10 Dec 2021 at 00:24, Laurent Pinchart wrote:
> > > On Thu, Dec 09, 2021 at 10:29:21AM +0000, Naushir Patuck wrote:
> > > > On Thu, 9 Dec 2021 at 10:25, Kieran Bingham wrote:
> > > > > Quoting Naushir Patuck (2021-12-09 10:07:43)
> > > > > > On Thu, 9 Dec 2021 at 09:39, Kieran Bingham wrote:
> > > > > > > Quoting Naushir Patuck (2021-12-08 15:15:27)
> > > > > > > > This change will allow the pipeline handler to enumerate and
> control Video
> > > > > > > > Mux or Bridge devices that may be attached between sensors
> and a particular
> > > > > > > > Unicam instance. Cascaded mux or bridge devices are also
> handled.
> > > > > > > >
> > > > > > > > A new member function enumerateVideoDevices(), called from
> registerCamera(), is
> > > > > > > > used to identify and open all mux and bridge subdevices
> present in the
> > > > > > > > sensor -> Unicam link.
> > > > > > > >
> > > > > > > > Relevent links are enabled/disabled and pad formats
> correctly set in configure()
> > > > > > > > before the camera is started.
> > > > > > > >
> > > > > > > > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > > > > > > > ---
> > > > > > > >  .../pipeline/raspberrypi/raspberrypi.cpp      | 78
> +++++++++++++++++++
> > > > > > > >  1 file changed, 78 insertions(+)
> > > > > > > >
> > > > > > > > diff --git
> a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > > > index 756878c70036..ca176ecb40ec 100644
> > > > > > > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > > > > > @@ -12,6 +12,7 @@
> > > > > > > >  #include <mutex>
> > > > > > > >  #include <queue>
> > > > > > > >  #include <unordered_set>
> > > > > > > > +#include <utility>
> > > > > > > >
> > > > > > > >  #include <libcamera/base/shared_fd.h>
> > > > > > > >  #include <libcamera/base/utils.h>
> > > > > > > > @@ -220,6 +221,11 @@ public:
> > > > > > > >         std::vector<RPi::Stream *> streams_;
> > > > > > > >         /* Stores the ids of the buffers mapped in the IPA.
> */
> > > > > > > >         std::unordered_set<unsigned int> ipaBuffers_;
> > > > > > > > +       /*
> > > > > > > > +        * Stores a cascade of Video Mux or Bridge devices
> between the sensor and
> > > > > > > > +        * Unicam together with media link across the
> entities.
> > > > > > > > +        */
> > > > > > > > +
>  std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink *>>
> bridgeDevices_;
> > > > > > > >
> > > > > > > >         /* DMAHEAP allocation helper. */
> > > > > > > >         RPi::DmaHeap dmaHeap_;
> > > > > > > > @@ -311,6 +317,7 @@ private:
> > > > > > > >         }
> > > > > > > >
> > > > > > > >         int registerCamera(MediaDevice *unicam, MediaDevice
> *isp, MediaEntity *sensorEntity);
> > > > > > > > +       void enumerateVideoDevices(RPiCameraData *data,
> MediaLink *link);
> > > > > > > >         int queueAllBuffers(Camera *camera);
> > > > > > > >         int prepareBuffers(Camera *camera);
> > > > > > > >         void freeBuffers(Camera *camera);
> > > > > > > > @@ -868,6 +875,25 @@ int
> PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
> > > > > > > >          */
> > > > > > > >         data->properties_.set(properties::ScalerCropMaximum,
> data->sensorInfo_.analogCrop);
> > > > > > > >
> > > > > > > > +       /* Setup the Video Mux/Bridge entities. */
> > > > > > > > +       for (auto &[device, link] : data->bridgeDevices_) {
> > > > > > > > +               /* Start by disabling all the sink pad links
> on the devices in the cascade. */
> > > > > > > > +               for (const MediaPad *p :
> device->entity()->pads()) {
> > > > > > > > +                       if (!(p->flags() &
> MEDIA_PAD_FL_SINK))
> > > > > > > > +                               continue;
> > > > > > > > +
> > > > > > > > +                       for (MediaLink *l : p->links())
> > > > > > > > +                               l->setEnabled(false);
> > >
> > > As an optimization, you could skip disabling the link that you will
> > > enable below.
> >
> > Ack.
> >
> > > > > > > > +               }
> > > > > > > > +
> > > > > > > > +               /* Finally enable the link, and setup the
> pad format. */
> > > > > > > > +               link->setEnabled(true);
> > > > > > >
> > > > > > > Isn't this going to enable /all/ bridge links in the cascade
> > > > > > > incorrectly?
> > > > > > >
> > > > > > >
> > > > > > >    ┌──────────┐
> > > > > > >    │  Unicam  │
> > > > > > >    └─────▲────┘
> > > > > > >          │
> > > > > > >      ┌───┴───┐
> > > > > > >      │  Mux  ◄───────┐
> > > > > > >      └──▲────┘       │
> > > > > > >         │            │
> > > > > > >   ┌─────┴───┐    ┌───┴───┐
> > > > > > >   │ Sensor1 │    │  Mux  │◄──┐
> > > > > > >   └─────────┘    └─▲─────┘   │
> > > > > > >                    │         │
> > > > > > >            ┌───────┴─┐   ┌───┴─────┐
> > > > > > >            │ Sensor2 │   │ Sensor3 │
> > > > > > >            └─────────┘   └─────────┘
> > > > > > >
> > > > > > > In that 'use case' we're now iterating over all bridges and
> enabling
> > > > > > > their link, I think which means we've just enabled both muxes,
> > > > > > > immediately after disabling them - even for Sensor1?
> > > > > > >
> > > > > > > Maybe I've mis-understood it, but I thought there would be
> something
> > > > > > > that would start at the desired sensor, and walk up the links
> to the
> > > > > > > unicam enabling those links (and only those) as it went up?
> > > > > > >
> > > > > > > The walk only has to be done once too, so perhaps a
> per-camera(sensor)
> > > > > > > vector of links to iterate and enable?
> > > > > > >
> > > > > > > Or maybe I'm missing the separation between the bridgeDevices_
> and the
> > > > > > > per-camera instances. But if that's already happening, I can't
> then see
> > > > > > > how each camera data clears all the bridges used by other
> cameras...
> > > > > >
> > > > > > Let me explain my intention, and you can then tell me if the
> code does
> > > > > > what I think it does :-)
> > > > > >
> > > > > > Each sensor (Sensor{1,2,3}) will register its own Camera object,
> and
> > > > > > in that object bridgeDevices_ will store the cascade of muxes
> between
> > > > > > the sensor and the Unicam port. So, for Sensor1, we store only 1
> mux,
> > > > > > and Sensor{2,3} will store both muxes. Together with the mux
> device,
> > > > > > we also store the entity to entity links.
> > > > > >
> > > > > > The above code goes through those stored entities, first
> disabling *all*
> > > > > > links on each device in the chain, and then selectively enabling
> > > > > > the specific links that are stored in bridgeDevices_ to link
> sensor
> > > > > > to Unicam across all intermedia muxes.  If Sensor1 is used, this
> > > > > > does mean that the Sensor{2,3} -> Mux links might not change
> > > > > > state but the Mux to Mux link will be disabled.  Similarly, if
> we are driving
> > > > > > Sensor3, the  Sensor{1,2} -> Mux link will be disabled.
> > > > >
> > > > > I think I see the obvious part I missed ;-)
> > > > >
> > > > > It doesn't matter what configuration Mux2 has as long as Mux1 only
> has
> > > > > Sensor1 link enabled!
> > > > >
> > > > > It might help to document that in the comments somehow somewhere?
> > > > > Particularly now that you've already written the explanation to me
> -
> > > > > perhaps it should be a block comment above enumerateVideoDevices.
> > > > >
> > > > > Feel free to take or add the ascii diagram, I think more pictures
> in
> > > > > our documentation are always helpful. It's really easy to make
> those
> > > > > block diagrams in ascii art at https://asciiflow.com.
> > > >
> > > > Sure, I'll add some comments through the code explaining it in more
> detail.
> > > >
> > > > > > > > +               const MediaPad *srcPad = link->sink();
> > > > > > > > +               ret = device->setFormat(srcPad->index(),
> &sensorFormat);
> > > > > > >
> > > > > > > This assignment of ret is in a loop, so earlier failures are
> going to
> > > > > > > get ignored, unchecked.
> > > > > >
> > > > > > This should not matter, as ret is only used in the loop to count
> successful
> > > > > > camera registrations.  The return value from match() will be
> false only if
> > > > > > 0 cameras were registered.
> > > > >
> > > > > So should we not even assign it?
> > > > > Do we need to report a warning if it failed to set the format?
> > > > >
> > > > > But aren't we here in configure() setting the format of the device
> to
> > > > > propogate the format?
> > > > >
> > > > > If we fail to setFormat in that case, then I think we should be
> saying
> > > > > the configure() call failed?
> > > >
> > > > Oops, my mistake.  I misread your original comment and what bit of
> > > > code it refers to!  This ret value *is* used for the return path,
> and must
> > > > be accounted for correctly as it is set in a loop! I'll fix this in
> the next
> > > > revision.
> > > >
> > > > > > > > +               LOG(RPI, Info) << "Configured media link on
> device " << device->entity()->name()
> > > > > > > > +                              << " at pad " <<
> srcPad->index();
> > > > > > > > +       }
> > > > > > > > +
> > > > > > > >         return ret;
> > > > > > > >  }
> > > > > > > >
> > > > > > > > @@ -1098,6 +1124,13 @@ int
> PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > > > > > > >         if (data->sensor_->init())
> > > > > > > >                 return -EINVAL;
> > > > > > > >
> > > > > > > > +       /*
> > > > > > > > +        * Enumerate all the Video Mux/Bridge devices across
> the sensor -> unicam
> > > > > > > > +        * link. There may be a cascade of devices in this
> link!
> > > > > > > > +        */
> > > > > > > > +       MediaLink *link =
> sensorEntity->getPadByIndex(0)->links()[0];
> > > > > > > > +       enumerateVideoDevices(data.get(), link);
> > > > > > > > +
> > > > > > > >         data->sensorFormats_ =
> populateSensorFormats(data->sensor_);
> > > > > > > >
> > > > > > > >         ipa::RPi::SensorConfig sensorConfig;
> > > > > > > > @@ -1224,6 +1257,51 @@ int
> PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> > > > > > > >         return 0;
> > > > > > > >  }
> > > > > > > >
> > > > > > > > +void
> PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data, MediaLink
> *link)
> > >
> > > This function accesses members of data but doesn't seem to access any
> > > member of PipelineHandlerRPi. Could it be moved to RPiCameraData ?
> >
> > Yes, I can do that.
> >
> > > > > > > > +{
> > > > > > > > +       const MediaPad *sinkPad = link->sink();
> > > > > > > > +       const MediaEntity *entity = sinkPad->entity();
> > > > > > > > +       bool unicamFound = false;
> > > > > > > > +
> > > > > > > > +       /* We only deal with Video Mux and Bridge devices in
> cascade. */
> > > > > > > > +       if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> > > > > > > > +           entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> > > > > > > > +               return;
> > > > > > > > +
> > > > > > > > +       LOG(RPI, Info) << "Found video mux device " <<
> entity->name()
> > > > > > > > +                      << " linked to sink pad " <<
> sinkPad->index();
> > > > > > > > +
> > > > > > > > +
> data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),link);
> > > > > > > > +       data->bridgeDevices_.back().first->open();
> > > > > > >
> > > > > > > Going through the above, I can't help but wonder if the
> bridgeDevices_
> > > > > > > should be stored as a single instance in the Pipeline handler
> (not each
> > > > > > > CameraData, we have one CameraData per camera right? if so,
> how does
> > > > > > > camera3 disable all the links? does it know about every path?)
> > > > > >
> > > > > > From my description earlier, bridgeDevices_ must be stored in
> the CameraData, as
> > > > > > it lists the devices in the path between the sensor and Unicam.
> And this is unique
> > > > > > per-sensor.  Again, this does mean that if we are using Sensor1,
> links for Sensor{2,3}
> > > > > > -> Mux are not changed, but the Mux->Mux link will be disabled.
> Do you think
> > > > > > that may not be appropriate leaving them enabled?
> > >
> > > I can't help but seeing lots of similarities with the simple pipeline
> > > handler, which also performs dynamic discovery of pipelines (all the
> way
> > > to the video node in that case, while in your case it would be all the
> > > way to the Unicam device). I wonder if we could share code between the
> > > two ? This could benefit the Raspberry Pi pipeline handler by providing
> > > a more generic version of format propagation through the pipeline
> > > (although that part may be more difficult to share).
> > >
> > > An important difference between the two implementations is that the
> > > simple pipeline handler opens the video node and subdevs once only,
> > > storing them in the pipeline handler instance, and only stores pointers
> > > to those objects in the camera data.
> >
> > I've had a very brief look at the simple pipeline handler.  I agree,
> there are
> > similarities between the two.  I see that the enumeration/discovery in
> the
> > simple pipeline handler is a fair bit more sophisticated in finding all
> available
> > entities, whereas the RPi case, I only care to look for a cascade of mux
> > or bridge devices.
> >
> > What were your thoughts on trying to share functionality between these
> two
> > (and indeed all) pipeline handlers?  Perhaps one way would be to have
> some
> > common code to create the media graph structure for any given media
> device?
> > This could include entities, pads and links represented in a common way
> for
> > pipeline handlers to use?  Then the RPi enumeration code would simply
> look
> > to find the devices it cares about. This is probably a bigger job than
> is required
> > for this change though.
>
> That's a very good question :-)
>
> I don't usually believe in designing helpers without at least a couple
> of use cases for them, that more often than not leads to bad designs.
> Now we have two examples of code that needs to parse a media graph, and
> I expect the exact same feature could be implemented by all pipeline
> handlers.
>
> Following the design-from-use-cases philosophy, I think we should focus
> on the need at hand. I think it would be able to share code that parses
> a media graph to locate sensors and paths from them all the way up to a
> given entity (Unicam in your case, any video node in the simple pipeline
> handler case), and store the paths in a shared data structure. Functions
> to then setup the links in the pipeline seem to also be good candidates
> for a common helper.
>
> Format configuration along the pipeline could also possibly be shared,
> but that seems more difficult, as the needs appear to be a bit
> different.
>
> I do agree this is a bit of yak shaving, as it's not strictly required
> to get this feature implemented, but we also have a growing technical
> debt. I was thus wondering if you think you could have time to
> experiment a little bit.
>

Sure, I'll see what I can come up with to have some general purpose
helpers dealing with media device enumeration/discovery.  In the meantime,
I'll post a new patch with the requested changes soon.

Regard,
Naush


>
> > > > > I missed that, and now it's obvious. If the first mux is only
> pointing
> > > > > to Sensor1, then indeed it doesn't matter what mux2 is configured
> to
> > > > > link to...
> > > > >
> > > > > So I think that's ok.
> > > > >
> > > > > > Please shout if this doesn't make sense, and something simpler
> might
> > > > > > equally work :-)
> > > > >
> > > > > It's all fine until someone adds a crossbar perhaps that might
> make it
> > > > > possible to do more crazy things ;-)
> > > > >
> > > > > But we don't need to worry about that now I dont' think.
> > > > >
> > > > > I think I'm still concerned about that ret during the loop in
> > > > > configure(). But with that resolved:
> > > > >
> > > > > Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> > > > >
> > > > > > > > +
> > > > > > > > +       for (const MediaPad *pad : entity->pads()) {
> > > > > > > > +               /*
> > > > > > > > +                * Iterate through all the sink pads down
> the cascade to find any
> > > > > > > > +                * other Video Mux and Bridge devices.
> > > > > > > > +                */
> > > > > > > > +               if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> > > > > > > > +                       continue;
> > > > > > > > +
> > > > > > > > +               for (MediaLink *l : pad->links()) {
> > > > > > > > +                       enumerateVideoDevices(data, l);
> > > > > > > > +                       if (l->sink()->entity()->name() ==
> "unicam-image")
> > > > > > > > +                               unicamFound = true;
> > > > > > > > +               }
> > > > > > > > +       }
> > > > > > > > +
> > > > > > > > +       /* This identifies the end of our entity enumeration
> recursion. */
> > > > > > > > +       if (link->source()->entity()->function() ==
> MEDIA_ENT_F_CAM_SENSOR) {
> > > > > > > > +               /*
> > > > > > > > +               * If Unicam is not at the end of this
> cascade, we cannot configure
> > > > > > > > +               * this topology automatically, so remove all
> entity references.
> > > > > > > > +               */
> > > > > > > > +               if (!unicamFound) {
> > > > > > > > +                       LOG(RPI, Warning) << "Cannot
> automatically configure this MC topology!";
> > > > > > > > +                       data->bridgeDevices_.clear();
> > > > > > > > +               }
> > > > > > > > +       }
> > > > > > > > +}
> > > > > > > > +
> > > > > > > >  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> > > > > > > >  {
> > > > > > > >         RPiCameraData *data = cameraData(camera);
>
> --
> Regards,
>
> Laurent Pinchart
>

Patch
diff mbox series

diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 756878c70036..ca176ecb40ec 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -12,6 +12,7 @@ 
 #include <mutex>
 #include <queue>
 #include <unordered_set>
+#include <utility>
 
 #include <libcamera/base/shared_fd.h>
 #include <libcamera/base/utils.h>
@@ -220,6 +221,11 @@  public:
 	std::vector<RPi::Stream *> streams_;
 	/* Stores the ids of the buffers mapped in the IPA. */
 	std::unordered_set<unsigned int> ipaBuffers_;
+	/*
+	 * Stores a cascade of Video Mux or Bridge devices between the sensor and
+	 * Unicam together with media link across the entities.
+	 */
+	std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink *>> bridgeDevices_;
 
 	/* DMAHEAP allocation helper. */
 	RPi::DmaHeap dmaHeap_;
@@ -311,6 +317,7 @@  private:
 	}
 
 	int registerCamera(MediaDevice *unicam, MediaDevice *isp, MediaEntity *sensorEntity);
+	void enumerateVideoDevices(RPiCameraData *data, MediaLink *link);
 	int queueAllBuffers(Camera *camera);
 	int prepareBuffers(Camera *camera);
 	void freeBuffers(Camera *camera);
@@ -868,6 +875,25 @@  int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
 	 */
 	data->properties_.set(properties::ScalerCropMaximum, data->sensorInfo_.analogCrop);
 
+	/* Setup the Video Mux/Bridge entities. */
+	for (auto &[device, link] : data->bridgeDevices_) {
+		/* Start by disabling all the sink pad links on the devices in the cascade. */
+		for (const MediaPad *p : device->entity()->pads()) {
+			if (!(p->flags() & MEDIA_PAD_FL_SINK))
+				continue;
+
+			for (MediaLink *l : p->links())
+				l->setEnabled(false);
+		}
+
+		/* Finally enable the link, and setup the pad format. */
+		link->setEnabled(true);
+		const MediaPad *srcPad = link->sink();
+		ret = device->setFormat(srcPad->index(), &sensorFormat);
+		LOG(RPI, Info) << "Configured media link on device " << device->entity()->name()
+			       << " at pad " << srcPad->index();
+	}
+
 	return ret;
 }
 
@@ -1098,6 +1124,13 @@  int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
 	if (data->sensor_->init())
 		return -EINVAL;
 
+	/*
+	 * Enumerate all the Video Mux/Bridge devices across the sensor -> unicam
+	 * link. There may be a cascade of devices in this link!
+	 */
+	MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
+	enumerateVideoDevices(data.get(), link);
+
 	data->sensorFormats_ = populateSensorFormats(data->sensor_);
 
 	ipa::RPi::SensorConfig sensorConfig;
@@ -1224,6 +1257,51 @@  int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
 	return 0;
 }
 
+void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data, MediaLink *link)
+{
+	const MediaPad *sinkPad = link->sink();
+	const MediaEntity *entity = sinkPad->entity();
+	bool unicamFound = false;
+
+	/* We only deal with Video Mux and Bridge devices in cascade. */
+	if (entity->function() != MEDIA_ENT_F_VID_MUX &&
+	    entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
+		return;
+
+	LOG(RPI, Info) << "Found video mux device " << entity->name()
+		       << " linked to sink pad " << sinkPad->index();
+
+	data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity), link);
+	data->bridgeDevices_.back().first->open();
+
+	for (const MediaPad *pad : entity->pads()) {
+		/*
+		 * Iterate through all the sink pads down the cascade to find any
+		 * other Video Mux and Bridge devices.
+		 */
+		if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
+			continue;
+
+		for (MediaLink *l : pad->links()) {
+			enumerateVideoDevices(data, l);
+			if (l->sink()->entity()->name() == "unicam-image")
+				unicamFound = true;
+		}
+	}
+
+	/* This identifies the end of our entity enumeration recursion. */
+	if (link->source()->entity()->function() == MEDIA_ENT_F_CAM_SENSOR) {
+		/*
+		* If Unicam is not at the end of this cascade, we cannot configure
+		* this topology automatically, so remove all entity references.
+		*/
+		if (!unicamFound) {
+			LOG(RPI, Warning) << "Cannot automatically configure this MC topology!";
+			data->bridgeDevices_.clear();
+		}
+	}
+}
+
 int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
 {
 	RPiCameraData *data = cameraData(camera);