diff options
author | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 12:17:53 -0700 |
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committer | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 15:44:42 -0700 |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml')
-rw-r--r-- | kernel/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/kernel/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml b/kernel/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml new file mode 100644 index 000000000..d0332f610 --- /dev/null +++ b/kernel/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml @@ -0,0 +1,129 @@ +<refentry id="vidioc-subscribe-event"> + <refmeta> + <refentrytitle>ioctl VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refname> + <refpurpose>Subscribe or unsubscribe event</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_event_subscription +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>Subscribe or unsubscribe V4L2 event. Subscribed events are + dequeued by using the &VIDIOC-DQEVENT; ioctl.</para> + + <table frame="none" pgwide="1" id="v4l2-event-subscription"> + <title>struct <structname>v4l2_event_subscription</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of the event, see <xref linkend="event-type" />. Note that +<constant>V4L2_EVENT_ALL</constant> can be used with VIDIOC_UNSUBSCRIBE_EVENT +for unsubscribing all events at once.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>id</structfield></entry> + <entry>ID of the event source. If there is no ID associated with + the event source, then set this to 0. Whether or not an event + needs an ID depends on the event type.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>Event flags, see <xref linkend="event-flags" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[5]</entry> + <entry>Reserved for future extensions. Drivers and applications + must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="event-flags"> + <title>Event Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_EVENT_SUB_FL_SEND_INITIAL</constant></entry> + <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 such as <constant>V4L2_EVENT_CTRL</constant>. + Other events will ignore this flag.</entry> + </row> + <row> + <entry><constant>V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK</constant></entry> + <entry>0x0002</entry> + <entry><para>If set, then events directly caused by an ioctl will also be sent to + the filehandle that called that ioctl. For example, changing a control using + &VIDIOC-S-CTRL; will cause a V4L2_EVENT_CTRL to be sent back to that same + filehandle. Normally such events are suppressed to prevent feedback loops + where an application changes a control to a one value and then another, and + then receives an event telling it that that control has changed to the first + value.</para> + + <para>Since it can't tell whether that event was caused by another application + or by the &VIDIOC-S-CTRL; call it is hard to decide whether to set the + control to the value in the event, or ignore it.</para> + + <para>Think carefully when you set this flag so you won't get into situations + like that.</para> + </entry> + </row> + </tbody> + </tgroup> + </table> + + </refsect1> + <refsect1> + &return-value; + </refsect1> +</refentry> |