Date: Thu, 2 Mar 2017 17:53:45 +0200
From: Sakari Ailus <sakari.ailus@iki.fi>
To: Steve Longerbeam <slongerbeam@gmail.com>
Cc: robh+dt@kernel.org, mark.rutland@arm.com, shawnguo@kernel.org,
        kernel@pengutronix.de, fabio.estevam@nxp.com, linux@armlinux.org.uk,
        mchehab@kernel.org, hverkuil@xs4all.nl, nick@shmanahar.org,
        markus.heiser@darmarIT.de, p.zabel@pengutronix.de,
        laurent.pinchart+renesas@ideasonboard.com, bparrot@ti.com,
        geert@linux-m68k.org, arnd@arndb.de, sudipm.mukherjee@gmail.com,
        minghsiu.tsai@mediatek.com, tiffany.lin@mediatek.com,
        jean-christophe.trotin@st.com, horms+renesas@verge.net.au,
        niklas.soderlund+renesas@ragnatech.se, robert.jarzmik@free.fr,
        songjun.wu@microchip.com, andrew-ct.chen@mediatek.com,
        gregkh@linuxfoundation.org, shuah@kernel.org,
        sakari.ailus@linux.intel.com, pavel@ucw.cz, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-media@vger.kernel.org, devel@driverdev.osuosl.org,
        Steve Longerbeam <steve_longerbeam@mentor.com>
Subject: Re: [PATCH v4 13/36] [media] v4l2: add a frame timeout event
Message-ID: <20170302155342.GJ3220@valkosipuli.retiisi.org.uk>
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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?

>      * - ``V4L2_EVENT_PRIVATE_START``
>        - 0x08000000
>        - Base event number for driver-private events.
> diff --git a/Documentation/media/videodev2.h.rst.exceptions b/Documentation/media/videodev2.h.rst.exceptions
> index e11a0d0..5b0f767 100644
> --- a/Documentation/media/videodev2.h.rst.exceptions
> +++ b/Documentation/media/videodev2.h.rst.exceptions
> @@ -459,6 +459,7 @@ replace define V4L2_EVENT_CTRL event-type
>  replace define V4L2_EVENT_FRAME_SYNC event-type
>  replace define V4L2_EVENT_SOURCE_CHANGE event-type
>  replace define V4L2_EVENT_MOTION_DET event-type
> +replace define V4L2_EVENT_FRAME_TIMEOUT event-type
>  replace define V4L2_EVENT_PRIVATE_START event-type
>  
>  replace define V4L2_EVENT_CTRL_CH_VALUE ctrl-changes-flags
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 46e8a2e3..e174c45 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -2132,6 +2132,7 @@ struct v4l2_streamparm {
>  #define V4L2_EVENT_FRAME_SYNC			4
>  #define V4L2_EVENT_SOURCE_CHANGE		5
>  #define V4L2_EVENT_MOTION_DET			6
> +#define V4L2_EVENT_FRAME_TIMEOUT		7
>  #define V4L2_EVENT_PRIVATE_START		0x08000000
>  
>  /* Payload for V4L2_EVENT_VSYNC */

-- 
Regards,

Sakari Ailus
e-mail: sakari.ailus@iki.fi	XMPP: sailus@retiisi.org.uk