[libcamera-devel] [PATCH v1] libcamera: Update v4l2 pixel format to libcamera pixel format mapping

[Vedant Paranjape]

Hi Laurent,

On Thu, 17 Jun, 2021, 10:24 Laurent Pinchart, <
laurent.pinchart at ideasonboard.com> wrote:

> On Thu, Jun 17, 2021 at 01:30:57PM +0900, paul.elder at ideasonboard.com
> wrote:
> > Hi Vedant,
> >
> > For the subject, maybe "libcamera: Fix V4L2 pixel format mapping for
> > XRGB32" ?
> >
> > On Thu, Jun 17, 2021 at 02:18:44AM +0530, Vedant Paranjape wrote:
> > > According to DRM FourCCs and linux kernel docs V4L2_PIX_FMT_XRGB32
> >
> > I find it odd that the DRM fourccs would document v4l2 pixel formats...
> >
> > > is BX24, but it was mapped to formats::XBGR8888, which is XB24.
>
> The patch is correct, but the explanation isn't. There are 4CC values
> that refer to different formats in V4L2 and DRM. We can't rely on 'XR24'
> in DRM referring to the same format as 'XR24' in V4L2.
>

Then what is the common denominator between DRM and V4L2 pix format we can
use to find a mapping between these ?

Also can you please help me with a right commit message. It seems tricky in
this case.

> > This patch fixes the mismatch of V4L2_PIX_FMT_XRGB32, i.e, matches it to
> > > formats::BGRX8888. Furthermore, this patch adds V4L2_PIX_FMT_RBGX32
> pixel
> >
> > "Additionally, add a mapping from V4L2_PIX_FMT_RGBX32 to
> formats::XBGR8888" ?
> >
> > Paul
> >
> > > format which is represented by XB24, and maps V4L2_PIX_FMT_RGBX32
> > > to formats::XBGR8888
> > >
> > > Linux kernel pixel format docs:
> https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/pixfmt-rgb.html#bits-per-component
> > > DRM FourCC pixel format docs:
> https://elixir.bootlin.com/linux/latest/source/include/uapi/drm/drm_fourcc.h#L150
> > >
> > > Signed-off-by: Vedant Paranjape <vedantparanjape160201 at gmail.com>
> > > ---
> > >  src/libcamera/v4l2_pixelformat.cpp | 3 ++-
>
> You also need to update formats.cpp.
>
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/src/libcamera/v4l2_pixelformat.cpp
> b/src/libcamera/v4l2_pixelformat.cpp
> > > index 166d93cf..e86788ed 100644
> > > --- a/src/libcamera/v4l2_pixelformat.cpp
> > > +++ b/src/libcamera/v4l2_pixelformat.cpp
> > > @@ -51,7 +51,8 @@ const std::map<V4L2PixelFormat, PixelFormat> vpf2pf{
> > >     { V4L2PixelFormat(V4L2_PIX_FMT_RGB24), formats::BGR888 },
> > >     { V4L2PixelFormat(V4L2_PIX_FMT_BGR24), formats::RGB888 },
> > >     { V4L2PixelFormat(V4L2_PIX_FMT_XBGR32), formats::XRGB8888 },
> > > -   { V4L2PixelFormat(V4L2_PIX_FMT_XRGB32), formats::XBGR8888 },
> > > +   { V4L2PixelFormat(V4L2_PIX_FMT_RGBX32), formats::XBGR8888 },
> > > +   { V4L2PixelFormat(V4L2_PIX_FMT_XRGB32), formats::BGRX8888 },
> > >     { V4L2PixelFormat(V4L2_PIX_FMT_RGBA32), formats::ABGR8888 },
> > >     { V4L2PixelFormat(V4L2_PIX_FMT_ABGR32), formats::ARGB8888 },
> > >     { V4L2PixelFormat(V4L2_PIX_FMT_ARGB32), formats::BGRA8888 },
>
> --
> Regards,
>
> Laurent Pinchart
>
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