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@kernel.org>
---
 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@kernel.org>

Hi Eugen

Thanks for the patch.

On Wed, 20 May 2026 at 16:37, 'Eugen Hristev' via kernel-list
<kernel-list@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@kernel.org>

Reviewed-by: Dave Stevenson <dave.stevenson@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@kernel.org>
>