Subject: Re: [PATCH v4 13/36] [media] v4l2: add a frame timeout event
To: Sakari Ailus <sakari.ailus@iki.fi>
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        Steve Longerbeam <steve_longerbeam@mentor.com>
From: Steve Longerbeam <slongerbeam@gmail.com>
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Date: Thu, 2 Mar 2017 15:07:21 -0800
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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@mentor.com>
>> ---
>>  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