[libcamera-devel,v2,4/4] libcamera: pipeline: Register device numbers with camera
diff mbox series

Message ID 20230511225833.361699-5-kieran.bingham@ideasonboard.com
State Superseded
Headers show
Series
  • libcamera: Add new Camera devices property
Related show

Commit Message

Kieran Bingham May 11, 2023, 10:58 p.m. UTC
Register the identified device numbers with each camera as the Devices
property.

This facilitates camera daemons or other systems to identify which
devices are being managed by libcamera, and can prevent duplication of
camera resources.

As the Devices property now provides this list of devices, use it
directly from within the CameraManager when adding a Camera rather than
passing it through the internal API.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 include/libcamera/internal/camera_manager.h |  3 +--
 src/libcamera/camera_manager.cpp            | 13 ++++++++-----
 src/libcamera/pipeline_handler.cpp          | 12 ++++++++++--
 3 files changed, 19 insertions(+), 9 deletions(-)

Comments

Jacopo Mondi May 13, 2023, 3:07 p.m. UTC | #1
Hi Kieran

On Thu, May 11, 2023 at 11:58:33PM +0100, Kieran Bingham via libcamera-devel wrote:
> Register the identified device numbers with each camera as the Devices
> property.
>
> This facilitates camera daemons or other systems to identify which
> devices are being managed by libcamera, and can prevent duplication of
> camera resources.

more than duplication isn't this about concurrent access to the same
resources ?

>
> As the Devices property now provides this list of devices, use it
> directly from within the CameraManager when adding a Camera rather than
> passing it through the internal API.
>
> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> ---
>  include/libcamera/internal/camera_manager.h |  3 +--
>  src/libcamera/camera_manager.cpp            | 13 ++++++++-----
>  src/libcamera/pipeline_handler.cpp          | 12 ++++++++++--
>  3 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/include/libcamera/internal/camera_manager.h b/include/libcamera/internal/camera_manager.h
> index 8386e90e0f60..061d2c5083b0 100644
> --- a/include/libcamera/internal/camera_manager.h
> +++ b/include/libcamera/internal/camera_manager.h
> @@ -29,8 +29,7 @@ public:
>  	Private();
>
>  	int start();
> -	void addCamera(std::shared_ptr<Camera> camera,
> -		       const std::vector<dev_t> &devnums) LIBCAMERA_TSA_EXCLUDES(mutex_);
> +	void addCamera(std::shared_ptr<Camera> camera) LIBCAMERA_TSA_EXCLUDES(mutex_);
>  	void removeCamera(std::shared_ptr<Camera> camera) LIBCAMERA_TSA_EXCLUDES(mutex_);
>
>  	/*
> diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp
> index 34f09a4d181b..df5fdede85da 100644
> --- a/src/libcamera/camera_manager.cpp
> +++ b/src/libcamera/camera_manager.cpp
> @@ -15,7 +15,9 @@
>  #include <libcamera/base/utils.h>
>
>  #include <libcamera/camera.h>
> +#include <libcamera/property_ids.h>
>
> +#include "libcamera/internal/camera.h"
>  #include "libcamera/internal/camera_manager.h"
>  #include "libcamera/internal/device_enumerator.h"
>  #include "libcamera/internal/pipeline_handler.h"
> @@ -151,19 +153,17 @@ void CameraManager::Private::cleanup()
>  /**
>   * \brief Add a camera to the camera manager
>   * \param[in] camera The camera to be added
> - * \param[in] devnums The device numbers to associate with \a camera
>   *
>   * This function is called by pipeline handlers to register the cameras they
>   * handle with the camera manager. Registered cameras are immediately made
>   * available to the system.
>   *
> - * \a devnums are used by the V4L2 compatibility layer to map V4L2 device nodes
> - * to Camera instances.
> + * Device numbers from the Devices property are used by the V4L2 compatibility
                          properties::Devices

> + * layer to map V4L2 device nodes to Camera instances.

I would also add here what you have reported in the commit message
about higher level frameworks

>   *
>   * \context This function shall be called from the CameraManager thread.
>   */
> -void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
> -				       const std::vector<dev_t> &devnums)
> +void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera)
>  {
>  	ASSERT(Thread::current() == this);
>
> @@ -178,6 +178,9 @@ void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
>  		}
>  	}
>
> +	Camera::Private *data = camera->_d();
> +	auto devnums = data->properties_.get(properties::Devices).value_or(std::vector<int64_t>{});

No need to get a pointer to the Private implementation to access the
Camera properties.

        auto devnums = camera->properties().get...

I would also have expected
        .value_or(Span<const int64_t>{});

does this work because of an implicit type conversion ?

> +
>  	cameras_.push_back(std::move(camera));
>
>  	unsigned int index = cameras_.size() - 1;
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index 49092ea88a58..0b5fac7ad113 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -17,6 +17,7 @@
>
>  #include <libcamera/camera.h>
>  #include <libcamera/framebuffer.h>
> +#include <libcamera/property_ids.h>
>
>  #include "libcamera/internal/camera.h"
>  #include "libcamera/internal/camera_manager.h"
> @@ -612,7 +613,7 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
>  	 * Walk the entity list and map the devnums of all capture video nodes
>  	 * to the camera.
>  	 */
> -	std::vector<dev_t> devnums;
> +	std::vector<int64_t> devnums;
>  	for (const std::shared_ptr<MediaDevice> &media : mediaDevices_) {
>  		for (const MediaEntity *entity : media->entities()) {
>  			if (entity->pads().size() == 1 &&
> @@ -624,7 +625,14 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
>  		}
>  	}
>
> -	manager_->_d()->addCamera(std::move(camera), devnums);
> +	/*
> +	 * Store the associated devices as a property of the camera to allow
> +	 * systems to identify which devices are managed by libcamera.
> +	 */
> +	Camera::Private *data = camera->_d();
> +	data->properties_.set(properties::Devices, devnums);
> +
> +	manager_->_d()->addCamera(std::move(camera));

nice

>  }
>
>  /**
> --
> 2.34.1
>
Kieran Bingham May 13, 2023, 3:44 p.m. UTC | #2
Quoting Jacopo Mondi (2023-05-13 16:07:54)
> Hi Kieran
> 
> On Thu, May 11, 2023 at 11:58:33PM +0100, Kieran Bingham via libcamera-devel wrote:
> > Register the identified device numbers with each camera as the Devices
> > property.
> >
> > This facilitates camera daemons or other systems to identify which
> > devices are being managed by libcamera, and can prevent duplication of
> > camera resources.
> 
> more than duplication isn't this about concurrent access to the same
> resources ?

No not specifically concurrent. It's (in the feature request) so that
pipewire doesn't create a video object for the same UVC camera through
both libcamera and V4L2 for instance. They don't have to be used
concurrently even - it's the fact that pipewire doesn't know if the
device is managed by libcamera - and it can be managed through both V4L2
and libcamera - so pipewire ends up showing two camera objects that are
actually the same device.

Technically both could be used (individually) but this lets pipewire
decide to only show one (and it's up to PW to decide which one it
selects between libcamera and v4l2 directly).



> 
> >
> > As the Devices property now provides this list of devices, use it
> > directly from within the CameraManager when adding a Camera rather than
> > passing it through the internal API.
> >
> > Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> > ---
> >  include/libcamera/internal/camera_manager.h |  3 +--
> >  src/libcamera/camera_manager.cpp            | 13 ++++++++-----
> >  src/libcamera/pipeline_handler.cpp          | 12 ++++++++++--
> >  3 files changed, 19 insertions(+), 9 deletions(-)
> >
> > diff --git a/include/libcamera/internal/camera_manager.h b/include/libcamera/internal/camera_manager.h
> > index 8386e90e0f60..061d2c5083b0 100644
> > --- a/include/libcamera/internal/camera_manager.h
> > +++ b/include/libcamera/internal/camera_manager.h
> > @@ -29,8 +29,7 @@ public:
> >       Private();
> >
> >       int start();
> > -     void addCamera(std::shared_ptr<Camera> camera,
> > -                    const std::vector<dev_t> &devnums) LIBCAMERA_TSA_EXCLUDES(mutex_);
> > +     void addCamera(std::shared_ptr<Camera> camera) LIBCAMERA_TSA_EXCLUDES(mutex_);
> >       void removeCamera(std::shared_ptr<Camera> camera) LIBCAMERA_TSA_EXCLUDES(mutex_);
> >
> >       /*
> > diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp
> > index 34f09a4d181b..df5fdede85da 100644
> > --- a/src/libcamera/camera_manager.cpp
> > +++ b/src/libcamera/camera_manager.cpp
> > @@ -15,7 +15,9 @@
> >  #include <libcamera/base/utils.h>
> >
> >  #include <libcamera/camera.h>
> > +#include <libcamera/property_ids.h>
> >
> > +#include "libcamera/internal/camera.h"
> >  #include "libcamera/internal/camera_manager.h"
> >  #include "libcamera/internal/device_enumerator.h"
> >  #include "libcamera/internal/pipeline_handler.h"
> > @@ -151,19 +153,17 @@ void CameraManager::Private::cleanup()
> >  /**
> >   * \brief Add a camera to the camera manager
> >   * \param[in] camera The camera to be added
> > - * \param[in] devnums The device numbers to associate with \a camera
> >   *
> >   * This function is called by pipeline handlers to register the cameras they
> >   * handle with the camera manager. Registered cameras are immediately made
> >   * available to the system.
> >   *
> > - * \a devnums are used by the V4L2 compatibility layer to map V4L2 device nodes
> > - * to Camera instances.
> > + * Device numbers from the Devices property are used by the V4L2 compatibility
>                           properties::Devices
> 
> > + * layer to map V4L2 device nodes to Camera instances.
> 
> I would also add here what you have reported in the commit message
> about higher level frameworks
> 
> >   *
> >   * \context This function shall be called from the CameraManager thread.
> >   */
> > -void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
> > -                                    const std::vector<dev_t> &devnums)
> > +void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera)
> >  {
> >       ASSERT(Thread::current() == this);
> >
> > @@ -178,6 +178,9 @@ void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
> >               }
> >       }
> >
> > +     Camera::Private *data = camera->_d();
> > +     auto devnums = data->properties_.get(properties::Devices).value_or(std::vector<int64_t>{});
> 
> No need to get a pointer to the Private implementation to access the
> Camera properties.
> 
>         auto devnums = camera->properties().get...

Oh yeah ! That's easier/cleaner ;-)

> 
> I would also have expected
>         .value_or(Span<const int64_t>{});
> 
> does this work because of an implicit type conversion ?

I expect so! I wish we had Laurents' default emtpy constructors to be
able to do 
	.value_or({}); directly :-(

> > +
> >       cameras_.push_back(std::move(camera));
> >
> >       unsigned int index = cameras_.size() - 1;
> > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > index 49092ea88a58..0b5fac7ad113 100644
> > --- a/src/libcamera/pipeline_handler.cpp
> > +++ b/src/libcamera/pipeline_handler.cpp
> > @@ -17,6 +17,7 @@
> >
> >  #include <libcamera/camera.h>
> >  #include <libcamera/framebuffer.h>
> > +#include <libcamera/property_ids.h>
> >
> >  #include "libcamera/internal/camera.h"
> >  #include "libcamera/internal/camera_manager.h"
> > @@ -612,7 +613,7 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
> >        * Walk the entity list and map the devnums of all capture video nodes
> >        * to the camera.
> >        */
> > -     std::vector<dev_t> devnums;
> > +     std::vector<int64_t> devnums;
> >       for (const std::shared_ptr<MediaDevice> &media : mediaDevices_) {
> >               for (const MediaEntity *entity : media->entities()) {
> >                       if (entity->pads().size() == 1 &&
> > @@ -624,7 +625,14 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
> >               }
> >       }
> >
> > -     manager_->_d()->addCamera(std::move(camera), devnums);
> > +     /*
> > +      * Store the associated devices as a property of the camera to allow
> > +      * systems to identify which devices are managed by libcamera.
> > +      */
> > +     Camera::Private *data = camera->_d();
> > +     data->properties_.set(properties::Devices, devnums);
> > +
> > +     manager_->_d()->addCamera(std::move(camera));
> 
> nice

Yes, this bit worked out nicely indeed.

> 
> >  }
> >
> >  /**
> > --
> > 2.34.1
> >
Kieran Bingham May 15, 2023, 12:39 p.m. UTC | #3
Quoting Kieran Bingham (2023-05-13 16:44:04)
> Quoting Jacopo Mondi (2023-05-13 16:07:54)
> > Hi Kieran
> > 
> > On Thu, May 11, 2023 at 11:58:33PM +0100, Kieran Bingham via libcamera-devel wrote:
> > > Register the identified device numbers with each camera as the Devices
> > > property.
> > >
> > > This facilitates camera daemons or other systems to identify which
> > > devices are being managed by libcamera, and can prevent duplication of
> > > camera resources.
> > 
> > more than duplication isn't this about concurrent access to the same
> > resources ?
> 
> No not specifically concurrent. It's (in the feature request) so that
> pipewire doesn't create a video object for the same UVC camera through
> both libcamera and V4L2 for instance. They don't have to be used
> concurrently even - it's the fact that pipewire doesn't know if the
> device is managed by libcamera - and it can be managed through both V4L2
> and libcamera - so pipewire ends up showing two camera objects that are
> actually the same device.
> 
> Technically both could be used (individually) but this lets pipewire
> decide to only show one (and it's up to PW to decide which one it
> selects between libcamera and v4l2 directly).
> 
> 
> 
> > 
> > >
> > > As the Devices property now provides this list of devices, use it
> > > directly from within the CameraManager when adding a Camera rather than
> > > passing it through the internal API.
> > >
> > > Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> > > ---
> > >  include/libcamera/internal/camera_manager.h |  3 +--
> > >  src/libcamera/camera_manager.cpp            | 13 ++++++++-----
> > >  src/libcamera/pipeline_handler.cpp          | 12 ++++++++++--
> > >  3 files changed, 19 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/include/libcamera/internal/camera_manager.h b/include/libcamera/internal/camera_manager.h
> > > index 8386e90e0f60..061d2c5083b0 100644
> > > --- a/include/libcamera/internal/camera_manager.h
> > > +++ b/include/libcamera/internal/camera_manager.h
> > > @@ -29,8 +29,7 @@ public:
> > >       Private();
> > >
> > >       int start();
> > > -     void addCamera(std::shared_ptr<Camera> camera,
> > > -                    const std::vector<dev_t> &devnums) LIBCAMERA_TSA_EXCLUDES(mutex_);
> > > +     void addCamera(std::shared_ptr<Camera> camera) LIBCAMERA_TSA_EXCLUDES(mutex_);
> > >       void removeCamera(std::shared_ptr<Camera> camera) LIBCAMERA_TSA_EXCLUDES(mutex_);
> > >
> > >       /*
> > > diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp
> > > index 34f09a4d181b..df5fdede85da 100644
> > > --- a/src/libcamera/camera_manager.cpp
> > > +++ b/src/libcamera/camera_manager.cpp
> > > @@ -15,7 +15,9 @@
> > >  #include <libcamera/base/utils.h>
> > >
> > >  #include <libcamera/camera.h>
> > > +#include <libcamera/property_ids.h>
> > >
> > > +#include "libcamera/internal/camera.h"
> > >  #include "libcamera/internal/camera_manager.h"
> > >  #include "libcamera/internal/device_enumerator.h"
> > >  #include "libcamera/internal/pipeline_handler.h"
> > > @@ -151,19 +153,17 @@ void CameraManager::Private::cleanup()
> > >  /**
> > >   * \brief Add a camera to the camera manager
> > >   * \param[in] camera The camera to be added
> > > - * \param[in] devnums The device numbers to associate with \a camera
> > >   *
> > >   * This function is called by pipeline handlers to register the cameras they
> > >   * handle with the camera manager. Registered cameras are immediately made
> > >   * available to the system.
> > >   *
> > > - * \a devnums are used by the V4L2 compatibility layer to map V4L2 device nodes
> > > - * to Camera instances.
> > > + * Device numbers from the Devices property are used by the V4L2 compatibility
> >                           properties::Devices
> > 
> > > + * layer to map V4L2 device nodes to Camera instances.
> > 
> > I would also add here what you have reported in the commit message
> > about higher level frameworks

I'm not going to do this because:

 - A) It's not relevant here. Only the V4L2 layer uses the
      camerasByDevnum_ parts. The registration of devnums into
      Properties::Devices is separate.

   B) I'd probably like to work out how we remove the camerasByDevnum_
      and update the V4L2 layer to use the newly available
      Properties::Devices and remove these extra mappings internally.

> > 
> > >   *
> > >   * \context This function shall be called from the CameraManager thread.
> > >   */
> > > -void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
> > > -                                    const std::vector<dev_t> &devnums)
> > > +void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera)
> > >  {
> > >       ASSERT(Thread::current() == this);
> > >
> > > @@ -178,6 +178,9 @@ void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
> > >               }
> > >       }
> > >
> > > +     Camera::Private *data = camera->_d();
> > > +     auto devnums = data->properties_.get(properties::Devices).value_or(std::vector<int64_t>{});
> > 
> > No need to get a pointer to the Private implementation to access the
> > Camera properties.
> > 
> >         auto devnums = camera->properties().get...
> 
> Oh yeah ! That's easier/cleaner ;-)

Done.


> 
> > 
> > I would also have expected
> >         .value_or(Span<const int64_t>{});
> > 
> > does this work because of an implicit type conversion ?
> 
> I expect so! I wish we had Laurents' default emtpy constructors to be
> able to do 
>         .value_or({}); directly :-(

Changed to Span<>


V3 imminent.

--
Kieran


> 
> > > +
> > >       cameras_.push_back(std::move(camera));
> > >
> > >       unsigned int index = cameras_.size() - 1;
> > > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > > index 49092ea88a58..0b5fac7ad113 100644
> > > --- a/src/libcamera/pipeline_handler.cpp
> > > +++ b/src/libcamera/pipeline_handler.cpp
> > > @@ -17,6 +17,7 @@
> > >
> > >  #include <libcamera/camera.h>
> > >  #include <libcamera/framebuffer.h>
> > > +#include <libcamera/property_ids.h>
> > >
> > >  #include "libcamera/internal/camera.h"
> > >  #include "libcamera/internal/camera_manager.h"
> > > @@ -612,7 +613,7 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
> > >        * Walk the entity list and map the devnums of all capture video nodes
> > >        * to the camera.
> > >        */
> > > -     std::vector<dev_t> devnums;
> > > +     std::vector<int64_t> devnums;
> > >       for (const std::shared_ptr<MediaDevice> &media : mediaDevices_) {
> > >               for (const MediaEntity *entity : media->entities()) {
> > >                       if (entity->pads().size() == 1 &&
> > > @@ -624,7 +625,14 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
> > >               }
> > >       }
> > >
> > > -     manager_->_d()->addCamera(std::move(camera), devnums);
> > > +     /*
> > > +      * Store the associated devices as a property of the camera to allow
> > > +      * systems to identify which devices are managed by libcamera.
> > > +      */
> > > +     Camera::Private *data = camera->_d();
> > > +     data->properties_.set(properties::Devices, devnums);
> > > +
> > > +     manager_->_d()->addCamera(std::move(camera));
> > 
> > nice
> 
> Yes, this bit worked out nicely indeed.
> 
> > 
> > >  }
> > >
> > >  /**
> > > --
> > > 2.34.1
> > >

Patch
diff mbox series

diff --git a/include/libcamera/internal/camera_manager.h b/include/libcamera/internal/camera_manager.h
index 8386e90e0f60..061d2c5083b0 100644
--- a/include/libcamera/internal/camera_manager.h
+++ b/include/libcamera/internal/camera_manager.h
@@ -29,8 +29,7 @@  public:
 	Private();
 
 	int start();
-	void addCamera(std::shared_ptr<Camera> camera,
-		       const std::vector<dev_t> &devnums) LIBCAMERA_TSA_EXCLUDES(mutex_);
+	void addCamera(std::shared_ptr<Camera> camera) LIBCAMERA_TSA_EXCLUDES(mutex_);
 	void removeCamera(std::shared_ptr<Camera> camera) LIBCAMERA_TSA_EXCLUDES(mutex_);
 
 	/*
diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp
index 34f09a4d181b..df5fdede85da 100644
--- a/src/libcamera/camera_manager.cpp
+++ b/src/libcamera/camera_manager.cpp
@@ -15,7 +15,9 @@ 
 #include <libcamera/base/utils.h>
 
 #include <libcamera/camera.h>
+#include <libcamera/property_ids.h>
 
+#include "libcamera/internal/camera.h"
 #include "libcamera/internal/camera_manager.h"
 #include "libcamera/internal/device_enumerator.h"
 #include "libcamera/internal/pipeline_handler.h"
@@ -151,19 +153,17 @@  void CameraManager::Private::cleanup()
 /**
  * \brief Add a camera to the camera manager
  * \param[in] camera The camera to be added
- * \param[in] devnums The device numbers to associate with \a camera
  *
  * This function is called by pipeline handlers to register the cameras they
  * handle with the camera manager. Registered cameras are immediately made
  * available to the system.
  *
- * \a devnums are used by the V4L2 compatibility layer to map V4L2 device nodes
- * to Camera instances.
+ * Device numbers from the Devices property are used by the V4L2 compatibility
+ * layer to map V4L2 device nodes to Camera instances.
  *
  * \context This function shall be called from the CameraManager thread.
  */
-void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
-				       const std::vector<dev_t> &devnums)
+void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera)
 {
 	ASSERT(Thread::current() == this);
 
@@ -178,6 +178,9 @@  void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
 		}
 	}
 
+	Camera::Private *data = camera->_d();
+	auto devnums = data->properties_.get(properties::Devices).value_or(std::vector<int64_t>{});
+
 	cameras_.push_back(std::move(camera));
 
 	unsigned int index = cameras_.size() - 1;
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 49092ea88a58..0b5fac7ad113 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -17,6 +17,7 @@ 
 
 #include <libcamera/camera.h>
 #include <libcamera/framebuffer.h>
+#include <libcamera/property_ids.h>
 
 #include "libcamera/internal/camera.h"
 #include "libcamera/internal/camera_manager.h"
@@ -612,7 +613,7 @@  void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
 	 * Walk the entity list and map the devnums of all capture video nodes
 	 * to the camera.
 	 */
-	std::vector<dev_t> devnums;
+	std::vector<int64_t> devnums;
 	for (const std::shared_ptr<MediaDevice> &media : mediaDevices_) {
 		for (const MediaEntity *entity : media->entities()) {
 			if (entity->pads().size() == 1 &&
@@ -624,7 +625,14 @@  void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
 		}
 	}
 
-	manager_->_d()->addCamera(std::move(camera), devnums);
+	/*
+	 * Store the associated devices as a property of the camera to allow
+	 * systems to identify which devices are managed by libcamera.
+	 */
+	Camera::Private *data = camera->_d();
+	data->properties_.set(properties::Devices, devnums);
+
+	manager_->_d()->addCamera(std::move(camera));
 }
 
 /**