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Diffstat (limited to 'Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml')
-rw-r--r-- | Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml | 130 |
1 files changed, 0 insertions, 130 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml deleted file mode 100644 index 5fd0ee78f880..000000000000 --- a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml +++ /dev/null @@ -1,130 +0,0 @@ -<refentry id="vidioc-subscribe-event"> - <refmeta> - <refentrytitle>ioctl VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refentrytitle> - &manvol; - </refmeta> - - <refnamediv> - <refname>VIDIOC_SUBSCRIBE_EVENT</refname> - <refname>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> |