[libcamera-devel] [PATCH v2 2/2] libcamera:camera_sensor, ipa: raspberrypi: Test readOnly() for HBLANK control

[Kieran Bingham]

Quoting Naushir Patuck via libcamera-devel (2022-12-02 12:40:05)
> Use ControlInfo::readOnly() to test if the camera sensor accepts V4L2_CID_HBLANK
> control changes. This replaces the current workaround where we test if the
> V4L2_CID_HBLANK min and max values are the same to determine if a control is
> read-only.
> 
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  src/ipa/raspberrypi/raspberrypi.cpp | 12 +-----------
>  src/libcamera/camera_sensor.cpp     | 14 ++------------
>  2 files changed, 3 insertions(+), 23 deletions(-)
> 
> diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
> index bead436def3c..57f01496fc44 100644
> --- a/src/ipa/raspberrypi/raspberrypi.cpp
> +++ b/src/ipa/raspberrypi/raspberrypi.cpp
> @@ -1239,17 +1239,7 @@ void IPARPi::applyAGC(const struct AgcStatus *agcStatus, ControlList &ctrls)
>         ctrls.set(V4L2_CID_EXPOSURE, exposureLines);
>         ctrls.set(V4L2_CID_ANALOGUE_GAIN, gainCode);
>  
> -       /*
> -        * At present, there is no way of knowing if a control is read-only.
> -        * As a workaround, assume that if the minimum and maximum values of
> -        * the V4L2_CID_HBLANK control are the same, it implies the control
> -        * is read-only. This seems to be the case for all the cameras our IPA
> -        * works with.
> -        *
> -        * \todo The control API ought to have a flag to specify if a control
> -        * is read-only which could be used below.
> -        */
> -       if (mode_.minLineLength != mode_.maxLineLength)
> +       if (!sensorCtrls_.at(V4L2_CID_HBLANK).readOnly())
>                 ctrls.set(V4L2_CID_HBLANK, static_cast<int32_t>(hblank));

Well, certainly once there's a .readOnly()...


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

>  }
>  
> diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> index ae3127d6b693..3785b6441b90 100644
> --- a/src/libcamera/camera_sensor.cpp
> +++ b/src/libcamera/camera_sensor.cpp
> @@ -185,20 +185,10 @@ int CameraSensor::init()
>          * Set HBLANK to the minimum to start with a well-defined line length,
>          * allowing IPA modules that do not modify HBLANK to use the sensor
>          * minimum line length in their calculations.
> -        *
> -        * At present, there is no way of knowing if a control is read-only.
> -        * As a workaround, assume that if the minimum and maximum values of
> -        * the V4L2_CID_HBLANK control are the same, it implies the control
> -        * is read-only.
> -        *
> -        * \todo The control API ought to have a flag to specify if a control
> -        * is read-only which could be used below.
>          */
>         const ControlInfo hblank = ctrls.infoMap()->at(V4L2_CID_HBLANK);
> -       const int32_t hblankMin = hblank.min().get<int32_t>();
> -       const int32_t hblankMax = hblank.max().get<int32_t>();
> -
> -       if (hblankMin != hblankMax) {
> +       if (!hblank.readOnly()) {
> +               const int32_t hblankMin = hblank.min().get<int32_t>();
>                 ControlList ctrl(subdev_->controls());
>  
>                 ctrl.set(V4L2_CID_HBLANK, hblankMin);
> -- 
> 2.25.1
>