[libcamera-devel,v4,2/5] libcamera: camera_sensor: Generate a sensor ID

9056 diff mbox series

Generate a constant and unique string ID for the sensor. The ID is
generated from information from the firmware description of the camera
image sensor. The ID is unique and persistent across reboots of the
system.

For OF based systems the ID is the full path of the sensors in the
device tree description. For ACPI based systems the ID is the ACPI
firmware nodes path. Both ID sources are guaranteed to be unique and
persistent as long as the firmware of the system is not changed.

A special case is needed to deal with the VIMC pipeline that implements
a virtual pipeline that is not backed by any hardware device and is
therefore not described in the device firmware.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
---
* Changes since v3
- Update commit message.
- Add description of how ID are generated to comment.
---
 include/libcamera/internal/camera_sensor.h |  4 +
 src/libcamera/camera_sensor.cpp            | 94 ++++++++++++++++++++++
 2 files changed, 98 insertions(+)

Hi Niklas,

On 29/07/2020 10:21, Niklas Söderlund wrote:
> Generate a constant and unique string ID for the sensor. The ID is
> generated from information from the firmware description of the camera
> image sensor. The ID is unique and persistent across reboots of the
> system.
> 
> For OF based systems the ID is the full path of the sensors in the
> device tree description. For ACPI based systems the ID is the ACPI
> firmware nodes path. Both ID sources are guaranteed to be unique and
> persistent as long as the firmware of the system is not changed.
> 
> A special case is needed to deal with the VIMC pipeline that implements
> a virtual pipeline that is not backed by any hardware device and is
> therefore not described in the device firmware.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
> ---
> * Changes since v3
> - Update commit message.
> - Add description of how ID are generated to comment.
> ---
>  include/libcamera/internal/camera_sensor.h |  4 +
>  src/libcamera/camera_sensor.cpp            | 94 ++++++++++++++++++++++
>  2 files changed, 98 insertions(+)
> 
> diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
> index 06c8292ca30129de..e0d2d9f63b47c2fe 100644
> --- a/include/libcamera/internal/camera_sensor.h
> +++ b/include/libcamera/internal/camera_sensor.h
> @@ -47,6 +47,7 @@ public:
>  	int init();
>  
>  	const std::string &model() const { return model_; }
> +	const std::string &id() const { return id_; }
>  	const MediaEntity *entity() const { return entity_; }
>  	const std::vector<unsigned int> &mbusCodes() const { return mbusCodes_; }
>  	const std::vector<Size> &sizes() const { return sizes_; }
> @@ -67,11 +68,14 @@ protected:
>  	std::string logPrefix() const override;
>  
>  private:
> +	int generateID();
> +
>  	const MediaEntity *entity_;
>  	std::unique_ptr<V4L2Subdevice> subdev_;
>  	unsigned int pad_;
>  
>  	std::string model_;
> +	std::string id_;
>  
>  	V4L2Subdevice::Formats formats_;
>  	Size resolution_;
> diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> index 350f49accad99c7b..a12d196ad898bb92 100644
> --- a/src/libcamera/camera_sensor.cpp
> +++ b/src/libcamera/camera_sensor.cpp
> @@ -9,10 +9,12 @@
>  
>  #include <algorithm>
>  #include <float.h>
> +#include <fstream>
>  #include <iomanip>
>  #include <limits.h>
>  #include <math.h>
>  #include <regex>
> +#include <sys/stat.h>
>  
>  #include <libcamera/property_ids.h>
>  
> @@ -204,6 +206,11 @@ int CameraSensor::init()
>  	if (ret < 0)
>  		return ret;
>  
> +	/* Generate a unique ID for the sensor. */
> +	ret = generateID();
> +	if (ret)
> +		return ret;
> +
>  	/* Retrieve and store the camera sensor properties. */
>  	const ControlInfoMap &controls = subdev_->controls();
>  	int32_t propertyValue;
> @@ -283,6 +290,26 @@ int CameraSensor::init()
>   * \return The sensor model name
>   */
>  
> +/**
> + * \fn CameraSensor::id()
> + * \brief Retrieve the sensor ID
> + *
> + * The sensor ID is a free-formed string that uniquely identifies the sensor in
> + * the system. The ID is persistent between different instances of libcamera and
> + * between resets of the system.
> + *
> + * For OF based systems the ID is the full path of the sensors in the device
> + * tree description. For ACPI based systems the ID is the ACPI firmware nodes
> + * path. Both ID sources are guaranteed to be unique and persistent as long as
> + * the firmware of the system is not changed.
> + *
> + * A special case is needed to deal with the VIMC pipeline that implements a
> + * virtual pipeline that is not backed by any hardware device and is therefore
> + * not described in the device firmware.

If my comment about generic catching of virtual hardware is worthy of
this series, this can be "A special case is needed to deal with virtual
pipelines..." or such.

But that could also be an 'on top' patch anyway.

> + *
> + * \return The sensor ID
> + */
> +
>  /**
>   * \fn CameraSensor::entity()
>   * \brief Retrieve the sensor media entity
> @@ -541,4 +568,71 @@ std::string CameraSensor::logPrefix() const
>  	return "'" + entity_->name() + "'";
>  }
>  
> +int CameraSensor::generateID()
> +{
> +	std::string path, devPath = subdev_->devicePath();
> +	struct stat statbuf;
> +
> +	/* Try to generate ID from OF device tree path.  */
> +	path = devPath + "/of_node";
> +	if (stat(path.c_str(), &statbuf) == 0) {
> +		char ofPath[PATH_MAX];
> +
> +		if (!realpath(path.c_str(), ofPath)) {
> +			LOG(CameraSensor, Error) << "Failed to read sensor OF based ID";
> +			return -EINVAL;
> +		}
> +
> +		id_ = ofPath;
> +		const std::string dropStr = "/sys/firmware/devicetree/";
> +		if (id_.find(dropStr) == 0)
> +			id_.erase(0, dropStr.length());
> +
> +		return 0;
> +	}
> +
> +	/* Try to generate ID from ACPI path. */
> +	path = devPath + "/firmware_node/path";
> +	if (stat(path.c_str(), &statbuf) == 0) {
> +		std::ifstream file(path.c_str());
> +
> +		if (!file.is_open()) {
> +			LOG(CameraSensor, Error) << "Failed to read sensor ACPI based ID";
> +			return -EINVAL;
> +		}
> +
> +		std::getline(file, id_);
> +		file.close();
> +
> +		return 0;
> +	}
> +
> +	/*
> +	 * VIMC is a virtual video pipeline not backed hardware and have no OF

s/have/has/

> +	 * or ACPI firmware nodes. Handle this pipeline as a special case and
> +	 * generate IDs based on the sensor model.
> +	 */


How about instead of making this specific to VIMC, make it the generic
'last chance/best-effort' fallthrough ?

> +	path = devPath + "/modalias";
> +	if (stat(path.c_str(), &statbuf) == 0) {
> +		std::ifstream file(path.c_str());
> +
> +		if (!file.is_open()) {
> +			LOG(CameraSensor, Error) << "Failed to read sensor ACPI based ID";
> +			return -EINVAL;
> +		}
> +
> +		std::string modalias;
> +		std::getline(file, modalias);
> +		file.close();
> +
> +		if (modalias == "platform:vimc") {
> +			id_ = "VIMC " + model();

This could then just be:
	id_ = modalias + model()

+ anything else desired to keep things more likely to be unique...


> +			return 0;
> +		}
> +	}

I'm being a little selfish of course, but it's because the 'out of tree'
vivid pipeline handler would not get handled here, and I had
hoped/intended that it could remain out of tree as an instructional
series to support new developers.

This would 'break' vivid otherwise.

Of course this could potentially also be on top if you don't want to
support it in this series.

Let me know in that case, as I think I'll then have to do it next time I
rebase the vivid series.

therefore, with/without making this generic (and the small grammatical
error fixed above)

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

> +
> +	LOG(CameraSensor, Error) << "Unknown sensor device type, can not generate ID";
> +	return -EINVAL;
> +}
> +
>  } /* namespace libcamera */
>

Hi Kieran,

Thanks for your comments.

On 2020-07-29 11:23:32 +0100, Kieran Bingham wrote:
> Hi Niklas,
> 
> On 29/07/2020 10:21, Niklas Söderlund wrote:
> > Generate a constant and unique string ID for the sensor. The ID is
> > generated from information from the firmware description of the camera
> > image sensor. The ID is unique and persistent across reboots of the
> > system.
> > 
> > For OF based systems the ID is the full path of the sensors in the
> > device tree description. For ACPI based systems the ID is the ACPI
> > firmware nodes path. Both ID sources are guaranteed to be unique and
> > persistent as long as the firmware of the system is not changed.
> > 
> > A special case is needed to deal with the VIMC pipeline that implements
> > a virtual pipeline that is not backed by any hardware device and is
> > therefore not described in the device firmware.
> > 
> > Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
> > Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
> > ---
> > * Changes since v3
> > - Update commit message.
> > - Add description of how ID are generated to comment.
> > ---
> >  include/libcamera/internal/camera_sensor.h |  4 +
> >  src/libcamera/camera_sensor.cpp            | 94 ++++++++++++++++++++++
> >  2 files changed, 98 insertions(+)
> > 
> > diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
> > index 06c8292ca30129de..e0d2d9f63b47c2fe 100644
> > --- a/include/libcamera/internal/camera_sensor.h
> > +++ b/include/libcamera/internal/camera_sensor.h
> > @@ -47,6 +47,7 @@ public:
> >  	int init();
> >  
> >  	const std::string &model() const { return model_; }
> > +	const std::string &id() const { return id_; }
> >  	const MediaEntity *entity() const { return entity_; }
> >  	const std::vector<unsigned int> &mbusCodes() const { return mbusCodes_; }
> >  	const std::vector<Size> &sizes() const { return sizes_; }
> > @@ -67,11 +68,14 @@ protected:
> >  	std::string logPrefix() const override;
> >  
> >  private:
> > +	int generateID();
> > +
> >  	const MediaEntity *entity_;
> >  	std::unique_ptr<V4L2Subdevice> subdev_;
> >  	unsigned int pad_;
> >  
> >  	std::string model_;
> > +	std::string id_;
> >  
> >  	V4L2Subdevice::Formats formats_;
> >  	Size resolution_;
> > diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> > index 350f49accad99c7b..a12d196ad898bb92 100644
> > --- a/src/libcamera/camera_sensor.cpp
> > +++ b/src/libcamera/camera_sensor.cpp
> > @@ -9,10 +9,12 @@
> >  
> >  #include <algorithm>
> >  #include <float.h>
> > +#include <fstream>
> >  #include <iomanip>
> >  #include <limits.h>
> >  #include <math.h>
> >  #include <regex>
> > +#include <sys/stat.h>
> >  
> >  #include <libcamera/property_ids.h>
> >  
> > @@ -204,6 +206,11 @@ int CameraSensor::init()
> >  	if (ret < 0)
> >  		return ret;
> >  
> > +	/* Generate a unique ID for the sensor. */
> > +	ret = generateID();
> > +	if (ret)
> > +		return ret;
> > +
> >  	/* Retrieve and store the camera sensor properties. */
> >  	const ControlInfoMap &controls = subdev_->controls();
> >  	int32_t propertyValue;
> > @@ -283,6 +290,26 @@ int CameraSensor::init()
> >   * \return The sensor model name
> >   */
> >  
> > +/**
> > + * \fn CameraSensor::id()
> > + * \brief Retrieve the sensor ID
> > + *
> > + * The sensor ID is a free-formed string that uniquely identifies the sensor in
> > + * the system. The ID is persistent between different instances of libcamera and
> > + * between resets of the system.
> > + *
> > + * For OF based systems the ID is the full path of the sensors in the device
> > + * tree description. For ACPI based systems the ID is the ACPI firmware nodes
> > + * path. Both ID sources are guaranteed to be unique and persistent as long as
> > + * the firmware of the system is not changed.
> > + *
> > + * A special case is needed to deal with the VIMC pipeline that implements a
> > + * virtual pipeline that is not backed by any hardware device and is therefore
> > + * not described in the device firmware.
> 
> If my comment about generic catching of virtual hardware is worthy of
> this series, this can be "A special case is needed to deal with virtual
> pipelines..." or such.
> 
> But that could also be an 'on top' patch anyway.
> 
> > + *
> > + * \return The sensor ID
> > + */
> > +
> >  /**
> >   * \fn CameraSensor::entity()
> >   * \brief Retrieve the sensor media entity
> > @@ -541,4 +568,71 @@ std::string CameraSensor::logPrefix() const
> >  	return "'" + entity_->name() + "'";
> >  }
> >  
> > +int CameraSensor::generateID()
> > +{
> > +	std::string path, devPath = subdev_->devicePath();
> > +	struct stat statbuf;
> > +
> > +	/* Try to generate ID from OF device tree path.  */
> > +	path = devPath + "/of_node";
> > +	if (stat(path.c_str(), &statbuf) == 0) {
> > +		char ofPath[PATH_MAX];
> > +
> > +		if (!realpath(path.c_str(), ofPath)) {
> > +			LOG(CameraSensor, Error) << "Failed to read sensor OF based ID";
> > +			return -EINVAL;
> > +		}
> > +
> > +		id_ = ofPath;
> > +		const std::string dropStr = "/sys/firmware/devicetree/";
> > +		if (id_.find(dropStr) == 0)
> > +			id_.erase(0, dropStr.length());
> > +
> > +		return 0;
> > +	}
> > +
> > +	/* Try to generate ID from ACPI path. */
> > +	path = devPath + "/firmware_node/path";
> > +	if (stat(path.c_str(), &statbuf) == 0) {
> > +		std::ifstream file(path.c_str());
> > +
> > +		if (!file.is_open()) {
> > +			LOG(CameraSensor, Error) << "Failed to read sensor ACPI based ID";
> > +			return -EINVAL;
> > +		}
> > +
> > +		std::getline(file, id_);
> > +		file.close();
> > +
> > +		return 0;
> > +	}
> > +
> > +	/*
> > +	 * VIMC is a virtual video pipeline not backed hardware and have no OF
> 
> s/have/has/
> 
> > +	 * or ACPI firmware nodes. Handle this pipeline as a special case and
> > +	 * generate IDs based on the sensor model.
> > +	 */
> 
> 
> How about instead of making this specific to VIMC, make it the generic
> 'last chance/best-effort' fallthrough ?

No, the idea is that we really should only allow known good devices. So 
I'm afraid a special case for the out-of-tree vivid pipeline is need. I 
think it would be rather simple tho, see below.

> 
> > +	path = devPath + "/modalias";
> > +	if (stat(path.c_str(), &statbuf) == 0) {
> > +		std::ifstream file(path.c_str());
> > +
> > +		if (!file.is_open()) {
> > +			LOG(CameraSensor, Error) << "Failed to read sensor ACPI based ID";
> > +			return -EINVAL;
> > +		}
> > +
> > +		std::string modalias;
> > +		std::getline(file, modalias);
> > +		file.close();
> > +
> > +		if (modalias == "platform:vimc") {
> > +			id_ = "VIMC " + model();
> 
> This could then just be:
> 	id_ = modalias + model()
> 
> + anything else desired to keep things more likely to be unique...

I picked this string for VIMC as it is the string used today and we can 
guarantee it's unique. I would not object to chancing this to your 
suggestion if that is the group suggestion.

I would however not like to have a generic fall-thru here. But adding 
support for more virtual hardware should be simple right?


    else if (modalias == "platfrom:vivid")
        id_ = "VIVID " ....;

> 
> 
> > +			return 0;
> > +		}
> > +	}
> 
> I'm being a little selfish of course, but it's because the 'out of tree'
> vivid pipeline handler would not get handled here, and I had
> hoped/intended that it could remain out of tree as an instructional
> series to support new developers.

Selfish is good, we all scratch out itches right :-) I feel your pain of 
maintaining an out-of-tree pipeline handler, I'm sorry this change 
effects that.

> 
> This would 'break' vivid otherwise.
> 
> Of course this could potentially also be on top if you don't want to
> support it in this series.
> 
> Let me know in that case, as I think I'll then have to do it next time I
> rebase the vivid series.

I don't intend to make this a generic fall-true unless I'm seriously 
pushed in that direction from the group :-)

> 
> therefore, with/without making this generic (and the small grammatical
> error fixed above)
> 
> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

Thanks!

> 
> > +
> > +	LOG(CameraSensor, Error) << "Unknown sensor device type, can not generate ID";
> > +	return -EINVAL;
> > +}
> > +
> >  } /* namespace libcamera */
> > 
> 
> -- 
> Regards
> --
> Kieran