[libcamera-devel] [PATCH v3 2/5] libcamera: camera_sensor: Add frame length limits to CameraSensorInfo

[Jacopo Mondi]

Hi Naush

On Thu, Jan 28, 2021 at 09:10:47AM +0000, Naushir Patuck wrote:
> Sensor frame length is made up of active and inactive (blanking) lines.
> The minimum and maximum frame length values may be used by pipeline
> handlers to limit frame durations based on the sensor mode capabilities.
>
> Store the minimum and maximum allowable frame length values (in lines)
> in the CameraSensorInfo structure. These values are computed in
> CameraSensor::sensorInfo() by querying the sensor subdevice
> V4L2_CID_VBLANK control limits. This in turn means that V4L2_CID_VBLANK
> is now a mandatory subdevice control.
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>

I like this!

Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>

Thanks
  j

> ---
>  include/libcamera/internal/camera_sensor.h |  3 ++
>  src/libcamera/camera_sensor.cpp            | 43 ++++++++++++++++++++--
>  test/ipa/ipa_wrappers_test.cpp             |  2 +
>  3 files changed, 44 insertions(+), 4 deletions(-)
>
> diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
> index fed36bf26e47..5d8c9b1a3121 100644
> --- a/include/libcamera/internal/camera_sensor.h
> +++ b/include/libcamera/internal/camera_sensor.h
> @@ -33,6 +33,9 @@ struct CameraSensorInfo {
>
>  	uint64_t pixelRate;
>  	uint32_t lineLength;
> +
> +	uint32_t minFrameLength;
> +	uint32_t maxFrameLength;
>  };
>
>  class CameraSensor : protected Loggable
> diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> index ab315bdc468c..f60d0cc9c6fa 100644
> --- a/src/libcamera/camera_sensor.cpp
> +++ b/src/libcamera/camera_sensor.cpp
> @@ -113,6 +113,36 @@ LOG_DEFINE_CATEGORY(CameraSensor)
>   * The total line length in pixel clock periods, including blanking.
>   */
>
> +/**
> + * \var CameraSensorInfo::minFrameLength
> + * \brief The minimum allowable frame length in units of lines
> + *
> + * The sensor frame length comprises of active output lines and blanking lines
> + * in a frame. The minimum frame length value dictates the minimum allowable
> + * frame duration of the sensor mode.
> + *
> + * To obtain the minimum frame duration:
> + *
> + * \verbatim
> +	frameDuration(s) = minFrameLength(lines) * lineLength(pixels) / pixelRate(pixels per second)
> +   \endverbatim
> + */
> +
> +/**
> + * \var CameraSensorInfo::maxFrameLength
> + * \brief The maximum allowable frame length in units of lines
> + *
> + * The sensor frame length comprises of active output lines and blanking lines
> + * in a frame. The maximum frame length value dictates the maximum allowable
> + * frame duration of the sensor mode.
> + *
> + * To obtain the maximum frame duration:
> + *
> + * \verbatim
> +	frameDuration(s) = maxFrameLength(lines) * lineLength(pixels) / pixelRate(pixels per second)
> +   \endverbatim
> + */
> +
>  /**
>   * \class CameraSensor
>   * \brief A camera sensor based on V4L2 subdevices
> @@ -699,12 +729,13 @@ int CameraSensor::sensorInfo(CameraSensorInfo *info) const
>  	info->outputSize = format.size;
>
>  	/*
> -	 * Retrieve the pixel rate and the line length through V4L2 controls.
> -	 * Support for the V4L2_CID_PIXEL_RATE and V4L2_CID_HBLANK controls is
> -	 * mandatory.
> +	 * Retrieve the pixel rate, line length and minimum/maximum frame
> +	 * duration through V4L2 controls. Support for the V4L2_CID_PIXEL_RATE,
> +	 * V4L2_CID_HBLANK and V4L2_CID_VBLANK controls is mandatory.
>  	 */
>  	ControlList ctrls = subdev_->getControls({ V4L2_CID_PIXEL_RATE,
> -						   V4L2_CID_HBLANK });
> +						   V4L2_CID_HBLANK,
> +						   V4L2_CID_VBLANK });
>  	if (ctrls.empty()) {
>  		LOG(CameraSensor, Error)
>  			<< "Failed to retrieve camera info controls";
> @@ -715,6 +746,10 @@ int CameraSensor::sensorInfo(CameraSensorInfo *info) const
>  	info->lineLength = info->outputSize.width + hblank;
>  	info->pixelRate = ctrls.get(V4L2_CID_PIXEL_RATE).get<int64_t>();
>
> +	const ControlInfo vblank = ctrls.infoMap()->at(V4L2_CID_VBLANK);
> +	info->minFrameLength = info->outputSize.height + vblank.min().get<int32_t>();
> +	info->maxFrameLength = info->outputSize.height + vblank.max().get<int32_t>();
> +
>  	return 0;
>  }
>
> diff --git a/test/ipa/ipa_wrappers_test.cpp b/test/ipa/ipa_wrappers_test.cpp
> index 47533d105d03..eb6d783e8489 100644
> --- a/test/ipa/ipa_wrappers_test.cpp
> +++ b/test/ipa/ipa_wrappers_test.cpp
> @@ -313,6 +313,8 @@ protected:
>  			.outputSize = { 2560, 1940 },
>  			.pixelRate = 96000000,
>  			.lineLength = 2918,
> +			.minFrameLength = 1940,
> +			.maxFrameLength = 2880
>  		};
>  		std::map<unsigned int, IPAStream> config{
>  			{ 1, { V4L2_PIX_FMT_YUYV, { 1024, 768 } } },
> --
> 2.25.1
>
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