Hi Laurent, Just one question to this patch: On Mon, 20 Jun 2016, Laurent Pinchart wrote: > The metadata buffer type is used to transfer metadata between userspace > and kernelspace through a V4L2 buffers queue. It comes with a new > metadata capture capability and format description. > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> > --- > Documentation/DocBook/media/v4l/dev-meta.xml | 93 +++++++++++++++++++++++++++ > Documentation/DocBook/media/v4l/v4l2.xml | 1 + > drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 19 ++++++ > drivers/media/v4l2-core/v4l2-dev.c | 16 +++-- > drivers/media/v4l2-core/v4l2-ioctl.c | 34 ++++++++++ > drivers/media/v4l2-core/videobuf2-v4l2.c | 3 + > include/media/v4l2-ioctl.h | 8 +++ > include/uapi/linux/videodev2.h | 14 ++++ > 8 files changed, 182 insertions(+), 6 deletions(-) > create mode 100644 Documentation/DocBook/media/v4l/dev-meta.xml > > diff --git a/Documentation/DocBook/media/v4l/dev-meta.xml b/Documentation/DocBook/media/v4l/dev-meta.xml > new file mode 100644 > index 000000000000..9b5b1fba2007 > --- /dev/null > +++ b/Documentation/DocBook/media/v4l/dev-meta.xml > @@ -0,0 +1,93 @@ > + <title>Metadata Interface</title> > + > + <note> > + <title>Experimental</title> > + <para>This is an <link linkend="experimental"> experimental </link> > + interface and may change in the future.</para> > + </note> > + > + <para> > +Metadata refers to any non-image data that supplements video frames with > +additional information. This may include statistics computed over the image > +or frame capture parameters supplied by the image source. This interface is > +intended for transfer of metadata to userspace and control of that operation. > + </para> > + > + <para> > +The metadata interface is implemented on video capture devices. The device can > +be dedicated to metadata or can implement both video and metadata capture as > +specified in its reported capabilities. > + </para> > + > + <section> > + <title>Querying Capabilities</title> > + > + <para> > +Devices supporting the metadata interface set the > +<constant>V4L2_CAP_META_CAPTURE</constant> flag in the > +<structfield>capabilities</structfield> field of &v4l2-capability; > +returned by the &VIDIOC-QUERYCAP; ioctl. That flag means the device can capture > +metadata to memory. > + </para> > + <para> > +At least one of the read/write or streaming I/O methods must be supported. > + </para> > + </section> > + > + <section> > + <title>Data Format Negotiation</title> > + > + <para> > +The metadata device uses the <link linkend="format">format</link> ioctls to > +select the capture format. The metadata buffer content format is bound to that > +selectable format. In addition to the basic > +<link linkend="format">format</link> ioctls, the &VIDIOC-ENUM-FMT; ioctl > +must be supported as well. Why does ENUM_FMT have to be supported? As far as I understand, you haven't implemented it for VSP1, I followed that example and haven't implemented it for UVC either. Thanks Guennadi
