Re: [PATCH v7 1/3] media: videodev2: Add flag to unconditionally enumerate pixel formats

[Benjamin Gaignard]

Le 11/10/2024 à 15:29, Hans Verkuil a écrit :
> Hi Benjamin,
>
> On 26/08/2024 19:24, Benjamin Gaignard wrote:
> > When the index is ORed with V4L2_FMTDESC_FLAG_ENUM_ALL the
> > driver clears the flag and enumerate all the possible formats,
> > ignoring any limitations from the current configuration.
> > Drivers which do not support this flag yet always return an EINVAL.
> >
> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> > ---
> > change in version 7:
> > - Rework documentation about which drivers should use the flag
> >
> >   .../media/v4l/vidioc-enum-fmt.rst              | 18 +++++++++++++++++-
> >   .../media/videodev2.h.rst.exceptions           |  1 +
> >   include/uapi/linux/videodev2.h                 |  3 +++
> >   3 files changed, 21 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
> > index 3adb3d205531..e39c87bcbfc3 100644
> > --- a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
> > +++ b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
> > @@ -85,7 +85,17 @@ the ``mbus_code`` field is handled differently:
> >       * - __u32
> >         - ``index``
> >         - Number of the format in the enumeration, set by the application.
> > -	This is in no way related to the ``pixelformat`` field.
> > +        This is in no way related to the ``pixelformat`` field.
> > +        When the index is ORed with ``V4L2_FMTDESC_FLAG_ENUM_ALL`` the
> > +        driver clears the flag and enumerates all the possible formats,
> > +        ignoring any limitations from the current configuration. Drivers
> > +        which do not support this flag always return an ``EINVAL``
> > +        error code.
> I would like to add: " without clearing this flag."
>
> > +        Formats enumerated when using ``V4L2_FMTDESC_FLAG_ENUM_ALL`` flag
> > +        shouldn't be used when calling :c:func:`VIDIOC_ENUM_FRAMESIZES`
> > +        or :c:func:`VIDIOC_ENUM_FRAMEINTERVALS`.
> > +        ``V4L2_FMTDESC_FLAG_ENUM_ALL`` should only be used by drivers that
> > +        can return different format list depending on this flag.
> >       * - __u32
> >         - ``type``
> >         - Type of the data stream, set by the application. Only these types
> > @@ -234,6 +244,12 @@ the ``mbus_code`` field is handled differently:
> >   	valid. The buffer consists of ``height`` lines, each having ``width``
> >   	Data Units of data and the offset (in bytes) between the beginning of
> >   	each two consecutive lines is ``bytesperline``.
> > +    * - ``V4L2_FMTDESC_FLAG_ENUM_ALL``
> > +      - 0x80000000
> > +      - When the applications ORs ``index`` with ``V4L2_FMTDESC_FLAG_ENUM_ALL`` flag
> > +        the driver enumerates all the possible pixel formats without taking care
> > +        of any already set configuration. Drivers which do not support this flag,
> > +        always return ``EINVAL``.
> Ditto.
>
> If you agree, then I can make that change myself, no need to post a new version.

Of I agree :-)

Thanks a lot.
Benjamin

> Regards,
>
> 	Hans
>
> >   
> >   Return Value
> >   ============
> > diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> > index bdc628e8c1d6..0a9ea9686c24 100644
> > --- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> > +++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
> > @@ -216,6 +216,7 @@ replace define V4L2_FMT_FLAG_CSC_YCBCR_ENC fmtdesc-flags
> >   replace define V4L2_FMT_FLAG_CSC_HSV_ENC fmtdesc-flags
> >   replace define V4L2_FMT_FLAG_CSC_QUANTIZATION fmtdesc-flags
> >   replace define V4L2_FMT_FLAG_META_LINE_BASED fmtdesc-flags
> > +replace define V4L2_FMTDESC_FLAG_ENUM_ALL fmtdesc-flags
> >   
> >   # V4L2 timecode types
> >   replace define V4L2_TC_TYPE_24FPS timecode-type
> > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> > index 4e91362da6da..421a30cb0c51 100644
> > --- a/include/uapi/linux/videodev2.h
> > +++ b/include/uapi/linux/videodev2.h
> > @@ -904,6 +904,9 @@ struct v4l2_fmtdesc {
> >   #define V4L2_FMT_FLAG_CSC_QUANTIZATION		0x0100
> >   #define V4L2_FMT_FLAG_META_LINE_BASED		0x0200
> >   
> > +/*  Format description flag, to be ORed with the index */
> > +#define V4L2_FMTDESC_FLAG_ENUM_ALL		0x80000000
> > +
> >   	/* Frame Size and frame rate enumeration */
> >   /*
> >    *	F R A M E   S I Z E   E N U M E R A T I O N