Re: [PATCH v3 3/4] media: v4l2-common: Add kernel-doc for v4l2_fill_pixfmt_mp_aligned()

[Jacopo Mondi <jacopo.mondi@ideasonboard.com>]

Hi Tommaso

On Wed, Jul 08, 2026 at 06:14:04PM +0200, Tommaso Merciai wrote:
> Replace the bare placeholder comment with a full kernel-doc block
> documenting all parameters, the function behaviour for both single
> memory plane (mem_planes == 1) and multiple memory plane (mem_planes > 1)
> formats, and the return value.
>
> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> ---
> v2->v3:
>  - Moved to PATCH 3/4
>  - Fixed documentation as suggested by Sven Püschel
>
> v1->v2:
>  - New patch
>
>  include/media/v4l2-common.h | 28 +++++++++++++++++++++++++++-
>  1 file changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
> index be4dd9762196..f2b0c336ac81 100644
> --- a/include/media/v4l2-common.h
> +++ b/include/media/v4l2-common.h
> @@ -591,7 +591,33 @@ static inline int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt,
>  	return v4l2_fill_pixfmt_aligned(pixfmt, pixelformat, width, height, 1);
>  }
>
> -/* @stride_alignment is a power of 2 value in bytes */
> +/**
> + * v4l2_fill_pixfmt_mp_aligned - Fill in a &struct v4l2_pix_format_mplane with
> + *	stride alignment requirements.
> + *
> + * @pixfmt: pointer to the &struct v4l2_pix_format_mplane to be filled
> + * @pixelformat: the V4L2 pixel format (V4L2_PIX_FMT_*)
> + * @width: image width in pixels
> + * @height: image height in pixels
> + * @stride_alignment: stride alignment in bytes; must be a power of 2
> + *
> + * Fills all fields of @pixfmt for the given pixel format, dimensions, and
> + * stride alignment.
> + *
> + * For formats stored in a single memory plane (mem_planes == 1), the
> + * behaviour matches v4l2_fill_pixfmt_aligned(): plane_fmt[0].bytesperline
> + * is set to the primary plane stride. The strides of all components are
> + * aligned to the @stride_alignment. To keep the chroma strides consistently
> + * derivable from the luma stride, strides may be aligned to a multiple of
> + * the @stride_alignment instead. plane_fmt[0].sizeimage covers all


I guess this

"To keep the chroma strides consistently derivable from the luma
stride, strides may be aligned to a multiple of the @stride_alignment
instead."

comes from teh v4l2_format_plane_stride() implementation.

I admit is not 100% clear to me why the chroma strides is multiplied
and to which format this applies. But this is not on this patch...

> + * component planes.
> + *
> + * For formats with multiple memory planes (mem_planes > 1), each plane's
> + * bytesperline is independently rounded up to @stride_alignment, and

and each plane's sizeimage is ..

> + * sizeimage is set to bytesperline multiplied by the plane height.
> + *
> + * Return: 0 on success, -EINVAL if @pixelformat is unknown.
> + */

Reviewed-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>

Thanks
  j

>  int v4l2_fill_pixfmt_mp_aligned(struct v4l2_pix_format_mplane *pixfmt,
>  				u32 pixelformat, u32 width, u32 height,
>  				u8 stride_alignment);
> --
> 2.54.0
>
>