Re: [PATCH v4 13/36] [media] v4l2: add a frame timeout event

[Steve Longerbeam]

On 03/02/2017 07:53 AM, Sakari Ailus wrote:
> Hi Steve,
>
> On Wed, Feb 15, 2017 at 06:19:15PM -0800, Steve Longerbeam wrote:
> > Add a new FRAME_TIMEOUT event to signal that a video capture or
> > output device has timed out waiting for reception or transmit
> > completion of a video frame.
> >
> > Signed-off-by: Steve Longerbeam <steve_longerbeam@xxxxxxxxxx>
> > ---
> >  Documentation/media/uapi/v4l/vidioc-dqevent.rst | 5 +++++
> >  Documentation/media/videodev2.h.rst.exceptions  | 1 +
> >  include/uapi/linux/videodev2.h                  | 1 +
> >  3 files changed, 7 insertions(+)
> >
> > diff --git a/Documentation/media/uapi/v4l/vidioc-dqevent.rst b/Documentation/media/uapi/v4l/vidioc-dqevent.rst
> > index 8d663a7..dd77d9b 100644
> > --- a/Documentation/media/uapi/v4l/vidioc-dqevent.rst
> > +++ b/Documentation/media/uapi/v4l/vidioc-dqevent.rst
> > @@ -197,6 +197,11 @@ call.
> >  	the regions changes. This event has a struct
> >  	:c:type:`v4l2_event_motion_det`
> >  	associated with it.
> > +    * - ``V4L2_EVENT_FRAME_TIMEOUT``
> > +      - 7
> > +      - This event is triggered when the video capture or output device
> > +	has timed out waiting for the reception or transmit completion of
> > +	a frame of video.
>
> As you're adding a new interface, I suppose you have an implementation
> around. How do you determine what that timeout should be?

The imx-media driver sets the timeout to 1 second, or 30 frame
periods at 30 fps.

Steve