Re: [RFC v5 05/15] media: Documentation: Add scaling and post-scaler crop for common raw

Lad, Prabhakar
2025-02-03T15:45:45Z

On Mon, Feb 3, 2025 at 8:59 AM Sakari Ailus
<sakari.ailus@linux.intel.com> wrote:
>
> Document scaling and post-scaler digital crop operations for the common
> raw sensor model.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
> .../media/v4l/subdev-config-model.rst | 24 +++++++++++++++----
> 1 file changed, 19 insertions(+), 5 deletions(-)
>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

Cheers,
Prabhakar

> diff --git a/Documentation/userspace-api/media/v4l/subdev-config-model.rst b/Documentation/userspace-api/media/v4l/subdev-config-model.rst
> index b0bd09772ceb..f15e5495cc34 100644
> --- a/Documentation/userspace-api/media/v4l/subdev-config-model.rst
> +++ b/Documentation/userspace-api/media/v4l/subdev-config-model.rst
> @@ -118,11 +118,18 @@ sub-sampling to achieve the desired size.
>
> The digital crop operation takes place after binning and sub-sampling. It is
> configured by setting the ``V4L2_SEL_TGT_CROP`` rectangle on (pad, stream) pair
> -0/0. The resulting image size is further output by the sensor.
> +0/0.
> +
> +The scaling operation is performed after the digital crop. It is configured by
> +setting the ``V4L2_SEL_TGT_COMPOSE`` rectangle on (pad, stream) pair 0/0,
> +relative to the digital crop.
>
> The sensor's output mbus code is configured by setting the format on the (pad,
> -stream) pair 0/0. When setting the format, always use the same width and height
> -as for the digital crop setting.
> +stream) pair 0/0. The width and height fields are used to configure post-scaler
> +digital crop if supported by the driver, affecting the right and bottom edges of
> +the frame. If post-scaler digital crop is not supported, the width and height
> +fields of the format will match the compose rectangle sizes applied on the same
> +0/0 (pad, stream) pair.
>
> Drivers may only support some of even none of these configurations, in which
> case they do not expose the corresponding selection rectangles. If any selection
> @@ -180,12 +187,19 @@ Also refer to :ref:`Selection targets <v4l2-selection-targets-table>`.
> - X
> - Digital crop. This rectangle is relative to the ``V4L2_SEL_TGT_COMPOSE``
> rectangle on (pad, stream) pair 1/0.
> + * - 0/0
> + - ``V4L2_SEL_TGT_COMPOSE``
> + - \-
> + - X
> + - Scaling. This rectangle is relative to the ``V4L2_SEL_TGT_CROP``
> + rectangle on (pad, stream) pair 0/0.
> * - 0/0
> - Format
> - X
> - X
> - - Image data source format. Always assign the width and height fields of
> - the format to the same values than for the ``V4L2_SEL_TGT_CROP``
> + - Image data source format and post-scaler crop. The width and height
> + fields of the format, used to configure post-scaler crop on the right
> + and bottom edges of the image, are related to the ``V4L2_SEL_TGT_COMPOSE``
> rectangle on (pad, stream) pair 0/0. The media bus code reflects the
> pixel data output of the sensor.
> * - 0/1
> --
> 2.39.5
>