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[media] v4l: events: Define V4L2_EVENT_FRAME_SYNC

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Define a frame sync event to tell user space when the reception of a frame
starts.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Sakari Ailus 2011-07-18 08:40:03 -03:00 committed by Mauro Carvalho Chehab
parent c9f88aa976
commit eab00a0da2
3 changed files with 47 additions and 3 deletions
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22
Documentation/DocBook/media/v4l/vidioc-dqevent.xml
View file

@ -86,6 +86,12 @@
<entry>Event data for event V4L2_EVENT_CTRL.
</entry>
</row>
<row>
<entry></entry>
<entry>&v4l2-event-frame-sync;</entry>
<entry><structfield>frame</structfield></entry>
<entry>Event data for event V4L2_EVENT_FRAME_SYNC.</entry>
</row>
<row>
<entry></entry>
<entry>__u8</entry>
@ -220,6 +226,22 @@
</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">

16
Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
View file

@ -138,6 +138,22 @@
field of the oldest event.</para>
</entry>
</row>
<row>
<entry><constant>V4L2_EVENT_FRAME_SYNC</constant></entry>
<entry>4</entry>
<entry>
<para>Triggered immediately when the reception of a
frame has begun. 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
frame interval in between them.</para>
</entry>
</row>
<row>
<entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry>
<entry>0x08000000</entry>

12
include/linux/videodev2.h
View file

@ -2006,6 +2006,7 @@ struct v4l2_streamparm {
#define V4L2_EVENT_VSYNC 1
#define V4L2_EVENT_EOS 2
#define V4L2_EVENT_CTRL 3
#define V4L2_EVENT_FRAME_SYNC 4
#define V4L2_EVENT_PRIVATE_START 0x08000000
/* Payload for V4L2_EVENT_VSYNC */
@ -2032,12 +2033,17 @@ struct v4l2_event_ctrl {
__s32 default_value;
};
struct v4l2_event_frame_sync {
__u32 frame_sequence;
};
struct v4l2_event {
__u32 type;
union {
struct v4l2_event_vsync vsync;
struct v4l2_event_ctrl ctrl;
__u8 data[64];
struct v4l2_event_vsync vsync;
struct v4l2_event_ctrl ctrl;
struct v4l2_event_frame_sync frame_sync;
__u8 data[64];
} u;
__u32 pending;
__u32 sequence;