On Thu May 21 00:44:10 2026 +0200, Sven Püschel wrote:
> 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.
>
> v4l2_format_plane_stride uses an unsigned int as argument type to avoid
> the later multiplication from overflowing the u8 value. All other places
> use u8, as no practical use cases for a larger alignment are known at
> the moment.
>
> Reviewed-by: Nicolas Dufresne <[email protected]>
> Signed-off-by: Sven Püschel <[email protected]>
> Signed-off-by: Nicolas Dufresne <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/v4l2-core/v4l2-common.c | 56 +++++++++++++++++++++++++++--------
include/media/v4l2-common.h | 4 +++
2 files changed, 48 insertions(+), 12 deletions(-)
---
diff --git a/drivers/media/v4l2-core/v4l2-common.c
b/drivers/media/v4l2-core/v4l2-common.c
index 3cc8b04e1ea6..65db7340ad38 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -432,14 +432,33 @@ 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,
unsigned int 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. To avoid hardware or software
+ * deriving a different stride for the composite plane,
+ * multiply the alignment accordingly.
+ *
+ * It assumes the following format properties:
+ * - bpp_div[0] == bpp_div[1]
+ * - The multiplication factor doesn't differ between the non y planes
+ * - The multiplication factor is a power of 2
+ */
+ if (info->mem_planes == 1 && info->comp_planes > 1) {
+ if (plane == 0)
+ byte_alignment *= DIV_ROUND_UP(info->hdiv *
info->bpp[0], info->bpp[1]);
+ else
+ byte_alignment *= DIV_ROUND_UP(info->bpp[1], info->hdiv
* info->bpp[0]);
+ }
+
+ 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,
@@ -453,9 +472,10 @@ 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);
}
@@ -476,8 +496,9 @@ 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;
@@ -494,23 +515,34 @@ 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,
@@ -530,12 +562,12 @@ 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 401d8506c24b..edd416178c33 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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