From 670027c507e99521d416994a18a498def9ef2ea3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?= Date: Sat, 22 Oct 2016 19:31:08 -0300 Subject: Linux-libre 4.8.3-gnu --- Documentation/DocBook/media/v4l/dev-event.xml | 43 --------------------------- 1 file changed, 43 deletions(-) delete mode 100644 Documentation/DocBook/media/v4l/dev-event.xml (limited to 'Documentation/DocBook/media/v4l/dev-event.xml') diff --git a/Documentation/DocBook/media/v4l/dev-event.xml b/Documentation/DocBook/media/v4l/dev-event.xml deleted file mode 100644 index 19f4becfa..000000000 --- a/Documentation/DocBook/media/v4l/dev-event.xml +++ /dev/null @@ -1,43 +0,0 @@ - Event Interface - - The V4L2 event interface provides a means for a 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. Changes in the value or state of a V4L2 control can also be - reported through events. - - - 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. - - The event subscriptions and event queues are specific to file - handles. Subscribing an event on one file handle does not affect - other file handles. - - 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. - - Starting with kernel 3.1 certain guarantees can be given with - regards to events: - - Each subscribed event has its own internal dedicated event queue. -This means that flooding of one event type will not interfere with other -event types. - - - If the internal event queue for a particular subscribed event -becomes full, then the oldest event in that queue will be dropped. - - - Where applicable, certain event types can ensure that the payload -of the oldest event that is about to be dropped will be merged with the payload -of the next oldest event. Thus ensuring that no information is lost, but only an -intermediate step leading up to that information. See the documentation for the -event you want to subscribe to whether this is applicable for that event or not. - - -- cgit v1.2.3