summaryrefslogtreecommitdiffstats
path: root/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
diff options
context:
space:
mode:
authorHans Verkuil <hans.verkuil@cisco.com>2011-06-18 06:58:29 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-07-27 17:53:34 -0300
commite969084030b03f4997d63b3f718ba814290e0705 (patch)
tree3f8e7f22c2318f9bd092d6b8d6f40f5d0d6c46fd /Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
parent1de7310ac9854101ecb9cdeed0f8bd5ac66cf55e (diff)
downloadop-kernel-dev-e969084030b03f4997d63b3f718ba814290e0705.zip
op-kernel-dev-e969084030b03f4997d63b3f718ba814290e0705.tar.gz
[media] DocBook: update V4L Event Interface section
Starting with v3.1 the V4L2 API provides certain guarantees with respect to events. Document these. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml')
-rw-r--r--Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml15
1 files changed, 11 insertions, 4 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
index 975f603..039a969 100644
--- a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
@@ -100,7 +100,7 @@
<entry><constant>V4L2_EVENT_VSYNC</constant></entry>
<entry>1</entry>
<entry>This event is triggered on the vertical sync.
- This event has &v4l2-event-vsync; associated with it.
+ This event has a &v4l2-event-vsync; associated with it.
</entry>
</row>
<row>
@@ -118,7 +118,7 @@
matches the control ID from which you want to receive events.
This event is triggered if the control's value changes, if a
button control is pressed or if the control's flags change.
- This event has &v4l2-event-ctrl; associated with it. This struct
+ This event has a &v4l2-event-ctrl; associated with it. This struct
contains much of the same information as &v4l2-queryctrl; and
&v4l2-control;.
@@ -126,6 +126,13 @@
&VIDIOC-S-EXT-CTRLS;, then the event will not be sent to
the file handle that called the ioctl function. This prevents
nasty feedback loops.
+
+ This event type will ensure that no information is lost when
+ more events are raised than there is room internally. In that
+ case the &v4l2-event-ctrl; of the second-oldest event is kept,
+ but the <structfield>changes</structfield> field of the
+ second-oldest event is ORed with the <structfield>changes</structfield>
+ field of the oldest event.
</entry>
</row>
<row>
@@ -147,8 +154,8 @@
<entry>0x0001</entry>
<entry>When this event is subscribed an initial event will be sent
containing the current status. This only makes sense for events
- that are triggered by a status change. Other events will ignore
- this flag.</entry>
+ that are triggered by a status change such as <constant>V4L2_EVENT_CTRL</constant>.
+ Other events will ignore this flag.</entry>
</row>
</tbody>
</tgroup>
OpenPOWER on IntegriCloud