Hi Hans, Thanks for the comments.
On Mon, 30 Oct 2017, Hans Verkuil wrote: > Hi Guennadi, > > On 07/28/2017 02:46 PM, Hans Verkuil wrote: > > On 07/28/2017 02:33 PM, Guennadi Liakhovetski wrote: > >> Add a pixel format, used by the UVC driver to stream metadata. > >> > >> Signed-off-by: Guennadi Liakhovetski <[email protected]> > >> --- > >> Documentation/media/uapi/v4l/meta-formats.rst | 1 + > >> Documentation/media/uapi/v4l/pixfmt-meta-uvc.rst | 39 > >> ++++++++++++++++++++++++ > >> include/uapi/linux/videodev2.h | 1 + > >> 3 files changed, 41 insertions(+) > >> create mode 100644 Documentation/media/uapi/v4l/pixfmt-meta-uvc.rst [snip] > >> diff --git a/include/uapi/linux/videodev2.h > >> b/include/uapi/linux/videodev2.h > >> index 45cf735..0aad91c 100644 > >> --- a/include/uapi/linux/videodev2.h > >> +++ b/include/uapi/linux/videodev2.h > >> @@ -682,6 +682,7 @@ struct v4l2_pix_format { > >> /* Meta-data formats */ > >> #define V4L2_META_FMT_VSP1_HGO v4l2_fourcc('V', 'S', 'P', 'H') /* > >> R-Car VSP1 1-D Histogram */ > >> #define V4L2_META_FMT_VSP1_HGT v4l2_fourcc('V', 'S', 'P', 'T') /* > >> R-Car VSP1 2-D Histogram */ > >> +#define V4L2_META_FMT_UVC v4l2_fourcc('U', 'V', 'C', 'H') /* UVC > >> Payload Header metadata */ > > I discussed this with Laurent last week and since the metadata for UVC starts > with a standard header followed by vendor-specific data it makes sense to > use V4L2_META_FMT_UVC for just the standard header. Any vendor specific > formats > should have their own fourcc which starts with the standard header followed by > the custom data. The UVC driver would enumerate both the standard and the > vendor > specific fourcc. This would allow generic UVC applications to use the standard > header. Applications that know about the vendor specific data can select the > vendor specific format. > > This change would make this much more convenient to use. Then the driver should be able to decide, which private fourcc code to use for each of those devices. A natural way to do that seems to be to put that in the .driver_info field of struct usb_device_id. For that I'd replace the current use of that field for quirks with a pointer to a struct in a separate patch. Laurent, would that be acceptable? Then add a field to that struct for a private metadata fourcc code. Thanks Guennadi > Regards, > > Hans > > >> /* priv field value to indicates that subsequent fields are valid. */ > >> #define V4L2_PIX_FMT_PRIV_MAGIC 0xfeedcafe
