[libcamera-devel] [PATCH v3 3/3] libcamera: pipeline: raspberrypi: Update sensor's V4L2_CID_NOTIFY_GAINS control

[Naushir Patuck]

Hi David,

Thank you for your work.

On Wed, 5 Jan 2022 at 15:55, David Plowman <david.plowman at raspberrypi.com>
wrote:

> If the sensor exposes the V4L2_CID_NOTIFY_GAINS control, assume it
> means the sensor wants to be told the latest colour gains.
>
> We store whether the control exists and if so its default value, to
> save us checking for it on every frame.
>
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
>

Reviewed-by: Naushir Patuck <naush at raspberrypi.com>


> ---
>  .../pipeline/raspberrypi/raspberrypi.cpp      | 31 +++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> index b5c687da..4adef952 100644
> --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> @@ -264,6 +264,12 @@ public:
>
>         unsigned int dropFrameCount_;
>
> +       /*
> +        * If set, this stores the value that represets a gain of one for
> +        * the V4L2_CID_NOTIFY_GAINS control.
> +        */
> +       std::optional<int32_t> notifyGainsUnity_;
> +
>  private:
>         void checkRequestCompleted();
>         void fillRequestMetadata(const ControlList &bufferControls,
> @@ -1191,6 +1197,15 @@ int PipelineHandlerRPi::registerCamera(MediaDevice
> *unicam, MediaDevice *isp)
>         /* Initialize the camera properties. */
>         data->properties_ = data->sensor_->properties();
>
> +       /*
> +        * The V4L2_CID_NOTIFY_GAINS control, if present, is used to
> inform the
> +        * sensor of the colour gains. It is defined to be a linear gain
> where
> +        * the default value represents a gain of exactly one.
> +        */
> +       auto it = data->sensor_->controls().find(V4L2_CID_NOTIFY_GAINS);
> +       if (it != data->sensor_->controls().end())
> +               data->notifyGainsUnity_ = it->second.def().get<int32_t>();
> +
>         /*
>          * Set a default value for the ScalerCropMaximum property to show
>          * that we support its use, however, initialise it to zero because
> @@ -1495,6 +1510,22 @@ void RPiCameraData::statsMetadataComplete(uint32_t
> bufferId, const ControlList &
>         Request *request = requestQueue_.front();
>         request->metadata().merge(controls);
>
> +       /*
> +        * Inform the sensor of the latest colour gains if it has the
> +        * V4L2_CID_NOTIFY_GAINS control (which means notifyGainsUnity_ is
> set).
> +        */
> +       if (notifyGainsUnity_ &&
> controls.contains(libcamera::controls::ColourGains)) {
> +               libcamera::Span<const float> colourGains =
> controls.get(libcamera::controls::ColourGains);
> +               /* The control wants linear gains in the order B, Gb, Gr,
> R. */
> +               ControlList ctrls(sensor_->controls());
> +               std::array<int32_t, 4> gains = {
> static_cast<int32_t>(colourGains[1] * *notifyGainsUnity_),
> +                                                *notifyGainsUnity_,
> *notifyGainsUnity_,
> +
> static_cast<int32_t>(colourGains[0] * *notifyGainsUnity_) };
> +               ctrls.set(V4L2_CID_NOTIFY_GAINS, Span<const int32_t>{
> gains });
> +
> +               sensor_->setControls(&ctrls);
> +       }
> +
>         state_ = State::IpaComplete;
>         handleState();
>  }
> --
> 2.30.2
>
>
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