[PATCH v5 05/29] media: v4l2-common: add v4l2_fill_pixfmt_mp_aligned helper
Nicolas Dufresne
nicolas at ndufresne.ca
Fri May 8 14:09:17 PDT 2026
Le mardi 28 avril 2026 à 11:00 +0200, Sven Püschel a écrit :
> Add a v4l2_fill_pixfmt_mp_aligned helper which allows the user to
> specify a custom stride alignment in bytes. This is necessary for
> hardware like the Rockchip RGA3, which requires the stride value to be
> aligned to a 16 bytes boundary.
>
> The code makes some assumptions about the v4l2 format to simplify the
> calculation. They currently hold for all known v4l2 formats.
>
> Signed-off-by: Sven Püschel <s.pueschel at pengutronix.de>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> ---
> drivers/media/v4l2-core/v4l2-common.c | 51 ++++++++++++++++++++++++++---------
> include/media/v4l2-common.h | 4 +++
> 2 files changed, 43 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> index 2b5ccedeb6841..d64d7e76c834d 100644
> --- a/drivers/media/v4l2-core/v4l2-common.c
> +++ b/drivers/media/v4l2-core/v4l2-common.c
> @@ -431,14 +431,28 @@ static inline unsigned int v4l2_format_block_height(const struct v4l2_format_inf
> }
>
> static inline unsigned int v4l2_format_plane_stride(const struct v4l2_format_info *info, int plane,
> - unsigned int width)
> + unsigned int width, u8 byte_alignment)
> {
> unsigned int hdiv = plane ? info->hdiv : 1;
> unsigned int aligned_width =
> ALIGN(width, v4l2_format_block_width(info, plane));
>
> - return DIV_ROUND_UP(aligned_width, hdiv) *
> - info->bpp[plane] / info->bpp_div[plane];
> + /*
> + * Formats with a single memory plane derive the stride of the
> + * other planes from the y stride. Due to chroma subsampling this
> + * may cause the other plane strides to break the byte_alignment.
> + * Increase the alignment if necessary to prevent this.
> + *
> + * It assumes the following format properties:
> + * - bpp_div[0] == bpp_div[1]
> + * - The multiplication factor doesn't differ between the non y planes
> + */
> + if (info->mem_planes == 1 && info->comp_planes > 1 && plane == 0)
> + byte_alignment *= info->hdiv * info->bpp[0] / info->bpp[1];
> +
> + return ALIGN(DIV_ROUND_UP(aligned_width, hdiv) * info->bpp[plane] /
> + info->bpp_div[plane],
> + byte_alignment);
> }
>
> static inline unsigned int v4l2_format_plane_height(const struct v4l2_format_info *info, int plane,
> @@ -452,9 +466,10 @@ static inline unsigned int v4l2_format_plane_height(const struct v4l2_format_inf
> }
>
> static inline unsigned int v4l2_format_plane_size(const struct v4l2_format_info *info, int plane,
> - unsigned int width, unsigned int height)
> + unsigned int width, unsigned int height,
> + u8 stride_alignment)
> {
> - return v4l2_format_plane_stride(info, plane, width) *
> + return v4l2_format_plane_stride(info, plane, width, stride_alignment) *
> v4l2_format_plane_height(info, plane, height);
> }
>
> @@ -475,8 +490,9 @@ void v4l2_apply_frmsize_constraints(u32 *width, u32 *height,
> }
> EXPORT_SYMBOL_GPL(v4l2_apply_frmsize_constraints);
>
> -int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt,
> - u32 pixelformat, u32 width, u32 height)
> +int v4l2_fill_pixfmt_mp_aligned(struct v4l2_pix_format_mplane *pixfmt,
> + u32 pixelformat, u32 width, u32 height,
> + u8 stride_alignment)
> {
> const struct v4l2_format_info *info;
> struct v4l2_plane_pix_format *plane;
> @@ -493,23 +509,34 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt,
>
> if (info->mem_planes == 1) {
> plane = &pixfmt->plane_fmt[0];
> - plane->bytesperline = v4l2_format_plane_stride(info, 0, width);
> + plane->bytesperline = v4l2_format_plane_stride(info, 0, width,
> + stride_alignment);
> plane->sizeimage = 0;
>
> for (i = 0; i < info->comp_planes; i++)
> plane->sizeimage +=
> - v4l2_format_plane_size(info, i, width, height);
> + v4l2_format_plane_size(info, i, width, height,
> + stride_alignment);
> } else {
> for (i = 0; i < info->comp_planes; i++) {
> plane = &pixfmt->plane_fmt[i];
> plane->bytesperline =
> - v4l2_format_plane_stride(info, i, width);
> + v4l2_format_plane_stride(info, i, width,
> + stride_alignment);
> plane->sizeimage = plane->bytesperline *
> v4l2_format_plane_height(info, i, height);
> }
> }
> return 0;
> }
> +EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt_mp_aligned);
> +
> +int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt,
> + u32 pixelformat, u32 width, u32 height)
> +{
> + return v4l2_fill_pixfmt_mp_aligned(pixfmt, pixelformat,
> + width, height, 1);
> +}
> EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt_mp);
>
> int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
> @@ -529,12 +556,12 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
> pixfmt->width = width;
> pixfmt->height = height;
> pixfmt->pixelformat = pixelformat;
> - pixfmt->bytesperline = v4l2_format_plane_stride(info, 0, width);
> + pixfmt->bytesperline = v4l2_format_plane_stride(info, 0, width, 1);
> pixfmt->sizeimage = 0;
>
> for (i = 0; i < info->comp_planes; i++)
> pixfmt->sizeimage +=
> - v4l2_format_plane_size(info, i, width, height);
> + v4l2_format_plane_size(info, i, width, height, 1);
> return 0;
> }
> EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt);
> diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
> index 401d8506c24b5..edd416178c333 100644
> --- a/include/media/v4l2-common.h
> +++ b/include/media/v4l2-common.h
> @@ -558,6 +558,10 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
> u32 width, u32 height);
> int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt, u32 pixelformat,
> u32 width, u32 height);
> +/* @stride_alignment is a power of 2 value in bytes */
> +int v4l2_fill_pixfmt_mp_aligned(struct v4l2_pix_format_mplane *pixfmt,
> + u32 pixelformat, u32 width, u32 height,
> + u8 stride_alignment);
>
> /**
> * v4l2_get_link_freq - Get link rate from transmitter
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