[libcamera-devel] [PATCH v2 5/7] libcamera: camera_sensor: Collect camera properties

[Niklas Söderlund]

Hi Jacopo,

Thanks for your work.

On 2019-08-27 11:50:05 +0200, Jacopo Mondi wrote:
> Store the camera sensor location and rotation by parsing the
> associated V4L2 controls.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  src/libcamera/camera_sensor.cpp       | 39 +++++++++++++++++++++++++++
>  src/libcamera/include/camera_sensor.h |  4 +++
>  2 files changed, 43 insertions(+)
> 
> diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> index a7670b449b31..fc7fdcdcaf5b 100644
> --- a/src/libcamera/camera_sensor.cpp
> +++ b/src/libcamera/camera_sensor.cpp
> @@ -89,6 +89,45 @@ int CameraSensor::init()
>  	if (ret < 0)
>  		return ret;
>  
> +	/* Retrieve and store the camera sensor properties. */
> +	V4L2ControlList controls({
> +		V4L2_CID_CAMERA_SENSOR_LOCATION,
> +		V4L2_CID_CAMERA_SENSOR_ROTATION,
> +	});
> +	ret = subdev_->getControls(&controls);
> +	if (ret) {
> +		LOG(CameraSensor, Error)
> +			<< "Failed to get camera sensor controls: " << ret;
> +		return ret;
> +	}

I still feel this is a bit harsh for the moment. If the sensor don't 
support V4L2_CID_CAMERA_SENSOR_LOCATION and
V4L2_CID_CAMERA_SENSOR_ROTATION this will fail and the camera is not 
registered with the system. I see two problems with this,

1. If the camera location is EXTERNAL is rotation really a mandatory 
   property?

2. I agree that in the future when the kernel support for 
   SENSOR_LOCATION have taken hold we can make it mandatory. For now 
   would it not be a good idea to set location to EXTERNAL if it's not 
   present and print a warning?

   I fear we will block this series for a very long time without easing 
   the constraints for a while.

> +
> +	V4L2Control *control = controls[V4L2_CID_CAMERA_SENSOR_LOCATION];
> +	int64_t value = control->value();
> +	switch (value) {
> +	case V4L2_LOCATION_EXTERNAL:
> +		location_ = CAMERA_LOCATION_EXTERNAL;
> +		break;
> +	case V4L2_LOCATION_FRONT:
> +		location_ = CAMERA_LOCATION_FRONT;
> +		break;
> +	case V4L2_LOCATION_BACK:
> +		location_ = CAMERA_LOCATION_BACK;
> +		break;
> +	default:
> +		LOG(CameraSensor, Error)
> +			<< "Unsupported camera location: " << value;
> +		return -EINVAL;
> +	}
> +
> +	control = controls[V4L2_CID_CAMERA_SENSOR_ROTATION];
> +	value = control->value();
> +	if (value < 0 || value > 360) {
> +		LOG(CameraSensor, Error)
> +			<< "Unsupported camera rotation: " << value;
> +		return -EINVAL;
> +	}
> +	rotation_ = value;
> +
>  	/* Enumerate and cache media bus codes and sizes. */
>  	const ImageFormats formats = subdev_->formats(0);
>  	if (formats.isEmpty()) {
> diff --git a/src/libcamera/include/camera_sensor.h b/src/libcamera/include/camera_sensor.h
> index fe033fb374c1..32d39127b275 100644
> --- a/src/libcamera/include/camera_sensor.h
> +++ b/src/libcamera/include/camera_sensor.h
> @@ -10,6 +10,7 @@
>  #include <string>
>  #include <vector>
>  
> +#include <libcamera/control_ids.h>
>  #include <libcamera/geometry.h>
>  
>  #include "log.h"
> @@ -55,6 +56,9 @@ private:
>  
>  	std::vector<unsigned int> mbusCodes_;
>  	std::vector<Size> sizes_;
> +
> +	CameraLocation location_;
> +	unsigned int rotation_;
>  };
>  
>  } /* namespace libcamera */
> -- 
> 2.23.0
> 
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-- 
Regards,
Niklas Söderlund