Hi Sakari,
On 11/01/2013 02:10 PM, Sakari Ailus wrote:
> Add an event to signal frame end. This is not necessarily the same timestamp
> as the video buffer done timestamp, and can be also subscribed by other
> processes than the one controlling streaming and buffer (de)queueing.
>
> Also make all event type constants appear as constants in documentation and
> move frame sync event struct documentation after all control event
> documentation.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> ---
> Hi folks,
>
> As we have a frame sync event that's being used to tell about the frame
> start, I thought of having a frame end event as well. This isn't exactly the
> same as a buffer ready event which could take place already earlier for
> instance if cropping is being done.
>
> I propose to use the id field for the purpose (V4L2_EVENT_FRAME_SYNC_START /
> V4L2_EVENT_FRAME_SYNC_END). The frame start event will retain its old id
> zero.
>
> Originally I think we thought of using the id field for the line, but
> now I think it's worth adding a distinct event for that purpose: line based
> events are typically triggered from other sources than line based events.
> Frame sync, in my opinion, matches better with frame start and frame end
> than to anything related to lines.
>
> So should line based events be supported, they should have their own event
> type and use the id field as the line number.
I have no objections to this patch. You do need to adapt drivers/media/platform/omap3isp/ispccdc.c
a bit since it is using the FRAME_SYNC event and so it should check the id field.
But will you also be upstreaming a driver that uses the SYNC_END?
I don't really want to merge this if nobody is using it.
Regards,
Hans
>
> Kind regards,
> Sakari
>
> Documentation/DocBook/media/v4l/vidioc-dqevent.xml | 58 +++++++++++++++-------
> .../DocBook/media/v4l/vidioc-subscribe-event.xml | 11 +++-
> include/uapi/linux/videodev2.h | 3 ++
> 3 files changed, 51 insertions(+), 21 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> index 89891ad..e258c6e 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> @@ -76,21 +76,22 @@
> <entry></entry>
> <entry>&v4l2-event-vsync;</entry>
> <entry><structfield>vsync</structfield></entry>
> - <entry>Event data for event V4L2_EVENT_VSYNC.
> + <entry>Event data for event <constant>V4L2_EVENT_VSYNC</constant>.
> </entry>
> </row>
> <row>
> <entry></entry>
> <entry>&v4l2-event-ctrl;</entry>
> <entry><structfield>ctrl</structfield></entry>
> - <entry>Event data for event V4L2_EVENT_CTRL.
> + <entry>Event data for event <constant>V4L2_EVENT_CTRL</constant>.
> </entry>
> </row>
> <row>
> <entry></entry>
> <entry>&v4l2-event-frame-sync;</entry>
> <entry><structfield>frame_sync</structfield></entry>
> - <entry>Event data for event V4L2_EVENT_FRAME_SYNC.</entry>
> + <entry>Event data for event <constant>V4L2_EVENT_FRAME_SYNC
> + </constant>.</entry>
> </row>
> <row>
> <entry></entry>
> @@ -226,22 +227,6 @@
> </tgroup>
> </table>
>
> - <table frame="none" pgwide="1" id="v4l2-event-frame-sync">
> - <title>struct <structname>v4l2_event_frame_sync</structname></title>
> - <tgroup cols="3">
> - &cs-str;
> - <tbody valign="top">
> - <row>
> - <entry>__u32</entry>
> - <entry><structfield>frame_sequence</structfield></entry>
> - <entry>
> - The sequence number of the frame being received.
> - </entry>
> - </row>
> - </tbody>
> - </tgroup>
> - </table>
> -
> <table pgwide="1" frame="none" id="changes-flags">
> <title>Changes</title>
> <tgroup cols="3">
> @@ -270,6 +255,41 @@
> </tbody>
> </tgroup>
> </table>
> +
> + <table frame="none" pgwide="1" id="v4l2-event-frame-sync">
> + <title>struct <structname>v4l2_event_frame_sync</structname></title>
> + <tgroup cols="3">
> + &cs-str;
> + <tbody valign="top">
> + <row>
> + <entry>__u32</entry>
> + <entry><structfield>frame_sequence</structfield></entry>
> + <entry>
> + The sequence number of the frame being received.
> + </entry>
> + </row>
> + </tbody>
> + </tgroup>
> + </table>
> +
> + <table pgwide="1" frame="none" id="v4l2-event-frame-sync-ids">
> + <title>Frame sync event IDs</title>
> + <tgroup cols="3">
> + &cs-def;
> + <tbody valign="top">
> + <row>
> + <entry><constant>V4L2_EVENT_FRAME_SYNC_START</constant></entry>
> + <entry>0x0000</entry>
> + <entry>Frame sync event delivered at frame start.</entry>
> + </row>
> + <row>
> + <entry><constant>V4L2_EVENT_FRAME_SYNC_END</constant></entry>
> + <entry>0x0001</entry>
> + <entry>Frame sync event delivered at frame end.</entry>
> + </row>
> + </tbody>
> + </tgroup>
> + </table>
> </refsect1>
> <refsect1>
> &return-value;
> diff --git a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
> index 5c70b61..aaa6fe1 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
> @@ -143,15 +143,22 @@
> <entry>4</entry>
> <entry>
> <para>Triggered immediately when the reception of a
> - frame has begun. This event has a
> + frame has begun or ended. This event has a
> &v4l2-event-frame-sync; associated with it.</para>
>
> <para>If the hardware needs to be stopped in the case of a
> buffer underrun it might not be able to generate this event.
> In such cases the <structfield>frame_sequence</structfield>
> field in &v4l2-event-frame-sync; will not be incremented. This
> - causes two consecutive frame sequence numbers to have n times
> + causes two consecutive frame sync events to have n times
> frame interval in between them.</para>
> +
> + <para>The <structfield>id</structfield> field must be set to
> + either <constant>V4L2_EVENT_FRAME_SYNC_START</constant> or
> + <constant>V4L2_EVENT_FRAME_SYNC_END</constant> which signify
> + the start of frame and end of frame, respectively. See
> + <xref linkend="v4l2-event-frame-sync-ids" /> for more
> + information.</para>
> </entry>
> </row>
> <row>
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 437f1b0..133957a 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -1760,6 +1760,9 @@ struct v4l2_event_ctrl {
> __s32 default_value;
> };
>
> +#define V4L2_EVENT_FRAME_SYNC_START 0
> +#define V4L2_EVENT_FRAME_SYNC_END 1
> +
> struct v4l2_event_frame_sync {
> __u32 frame_sequence;
> };
>
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