[PATCH] media: bcm2835-unicam: Fix pipeline wrong validation for unpacked formats

[Dave Stevenson]

Hi Eugen

Thanks for the patch.

On Wed, 20 May 2026 at 16:37, 'Eugen Hristev' via kernel-list
<kernel-list at raspberrypi.com> wrote:
>
> The commit
> 08f9794d9b79 ("media: bcm2835-unicam: Fix RGB format / mbus code association")
> introduced a check to see whether the format requested is the same as the
> fourcc in the format list.
>
> However, this breaks the case when userspace requested an unpacked fourcc,
> e.g. RG10.
>
> Unicam can work with or without unpacking pixels, e.g. pRAA or RG10, depending
> on what userspace requests.
> In the unpacking case, a dedicated register is being set.
>
> If the userspace requests pRAA, this works, because the check validates the
> pipeline:
>
> v4l2-ctl -d /dev/video0 --set-fmt-video=width=3280,height=2464,pixelformat=pRAA \
>  --stream-mmap --stream-count=1 --stream-to=frame.raw
>
> but, with
> v4l2-ctl -d /dev/video0 --set-fmt-video=width=3280,height=2464,pixelformat=RG10 \
> --stream-mmap --stream-count=1 --stream-to=frame.raw
>
> unicam complains at validation level:
>
> image: format mismatch: 0x300f <=> RG10 little-endian (0x30314752)
>
> This should work, because MEDIA_BUS_FMT_SRGGB10_1X10 can be packed into either
> RG10 or pRAA depending on the packing register.
>
> To fix this, modified the condition check to also allow in the case when
> requested format (fmt->pixelformat) is equal to fmtinfo->unpacked_fourcc.
>
> Fixes: 08f9794d9b79 ("media: bcm2835-unicam: Fix RGB format / mbus code association")
> Signed-off-by: Eugen Hristev <ehristev at kernel.org>

Reviewed-by: Dave Stevenson <dave.stevenson at raspberrypi.com>

> ---
>  drivers/media/platform/broadcom/bcm2835-unicam.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/broadcom/bcm2835-unicam.c b/drivers/media/platform/broadcom/bcm2835-unicam.c
> index 8d28ba0b59a3..cc7627e9a51a 100644
> --- a/drivers/media/platform/broadcom/bcm2835-unicam.c
> +++ b/drivers/media/platform/broadcom/bcm2835-unicam.c
> @@ -2158,7 +2158,8 @@ static int unicam_video_link_validate(struct media_link *link)
>                  * In order to allow the applications using the old behaviour to
>                  * run, let's accept the old combination, but warn about it.
>                  */
> -               if (fmtinfo->fourcc != fmt->pixelformat) {
> +               if (fmt->pixelformat != fmtinfo->fourcc &&
> +                   fmt->pixelformat != fmtinfo->unpacked_fourcc) {
>                         if ((fmt->pixelformat == V4L2_PIX_FMT_BGR24 &&
>                              format->code == MEDIA_BUS_FMT_BGR888_1X24) ||
>                             (fmt->pixelformat == V4L2_PIX_FMT_RGB24 &&
>
> ---
> base-commit: e98d21c170b01ddef366f023bbfcf6b31509fa83
> change-id: 20260520-bcmpi-2c4850314e21
>
> Best regards,
> --
> Eugen Hristev <ehristev at kernel.org>
>