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

[Sakari Ailus]

On Thu, Jul 16, 2026 at 11:12:40AM +0300, Laurent Pinchart wrote:
> On Thu, Jul 16, 2026 at 10:22:03AM +0300, Eugen Hristev wrote:
> > On 6/3/26 09:48, Jai Luthra wrote:
> > > Quoting Eugen Hristev (2026-05-20 21:07:00)
> > >> 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@xxxxxxxxxx>
> > >> ---
> > >>  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 &&
> > >>
> > > 
> > > Reviewed-by: Jai Luthra <jai.luthra@xxxxxxxxxxxxxxxx>
> > > 
> > 
> > Hi Sakari,
> > 
> > I saw you taking some of the patches on unicam, this one is the most
> > important as all unpacked formats are basically broken for a very long
> > time (months) and the patch is pending for quite some time.
> > 
> > This should also go in stable as some older versions also affected.
> 
> The commit message should include
> 
> Cc: stable@xxxxxxxxxxxxxxx
> 
> after the Fixes: tag. Sakari can likely add that when applying.

Yes. I expect to pick the patch later this week.

-- 
Sakari Ailus