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author | Jens Axboe <jens.axboe@oracle.com> | 2010-05-21 21:27:26 +0200 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2010-05-21 21:27:26 +0200 |
commit | ee9a3607fb03e804ddf624544105f4e34260c380 (patch) | |
tree | ce41b6e0fa10982a306f6c142a92dbf3c9961284 /Documentation/DocBook/v4l/dev-event.xml | |
parent | pipe: set lower and upper limit on max pages in the pipe page array (diff) | |
parent | Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jac... (diff) | |
download | linux-ee9a3607fb03e804ddf624544105f4e34260c380.tar.xz linux-ee9a3607fb03e804ddf624544105f4e34260c380.zip |
Merge branch 'master' into for-2.6.35
Conflicts:
fs/ext3/fsync.c
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'Documentation/DocBook/v4l/dev-event.xml')
-rw-r--r-- | Documentation/DocBook/v4l/dev-event.xml | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/dev-event.xml b/Documentation/DocBook/v4l/dev-event.xml new file mode 100644 index 000000000000..be5a98fb4fab --- /dev/null +++ b/Documentation/DocBook/v4l/dev-event.xml @@ -0,0 +1,31 @@ + <title>Event Interface</title> + + <para>The V4L2 event interface provides means for user to get + immediately notified on certain conditions taking place on a device. + This might include start of frame or loss of signal events, for + example. + </para> + + <para>To receive events, the events the user is interested in first must + be subscribed using the &VIDIOC-SUBSCRIBE-EVENT; ioctl. Once an event is + subscribed, the events of subscribed types are dequeueable using the + &VIDIOC-DQEVENT; ioctl. Events may be unsubscribed using + VIDIOC_UNSUBSCRIBE_EVENT ioctl. The special event type V4L2_EVENT_ALL may + be used to unsubscribe all the events the driver supports.</para> + + <para>The event subscriptions and event queues are specific to file + handles. Subscribing an event on one file handle does not affect + other file handles. + </para> + + <para>The information on dequeueable events is obtained by using select or + poll system calls on video devices. The V4L2 events use POLLPRI events on + poll system call and exceptions on select system call. </para> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> |