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Diffstat (limited to 'Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml')
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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 5c70b616d818..000000000000 --- a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml +++ /dev/null @@ -1,206 +0,0 @@ -<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.</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 frame="none" pgwide="1" id="event-type"> - <title>Event Types</title> - <tgroup cols="3"> - &cs-def; - <tbody valign="top"> - <row> - <entry><constant>V4L2_EVENT_ALL</constant></entry> - <entry>0</entry> - <entry>All events. V4L2_EVENT_ALL is valid only for - VIDIOC_UNSUBSCRIBE_EVENT for unsubscribing all events at once. - </entry> - </row> - <row> - <entry><constant>V4L2_EVENT_VSYNC</constant></entry> - <entry>1</entry> - <entry>This event is triggered on the vertical sync. - This event has a &v4l2-event-vsync; associated with it. - </entry> - </row> - <row> - <entry><constant>V4L2_EVENT_EOS</constant></entry> - <entry>2</entry> - <entry>This event is triggered when the end of a stream is reached. - This is typically used with MPEG decoders to report to the application - when the last of the MPEG stream has been decoded. - </entry> - </row> - <row> - <entry><constant>V4L2_EVENT_CTRL</constant></entry> - <entry>3</entry> - <entry><para>This event requires that the <structfield>id</structfield> - 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 a &v4l2-event-ctrl; associated with it. This struct - contains much of the same information as &v4l2-queryctrl; and - &v4l2-control;.</para> - - <para>If the event is generated due to a call to &VIDIOC-S-CTRL; or - &VIDIOC-S-EXT-CTRLS;, then the event will <emphasis>not</emphasis> be sent to - the file handle that called the ioctl function. This prevents - nasty feedback loops. If you <emphasis>do</emphasis> want to get the - event, then set the <constant>V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK</constant> - flag. - </para> - - <para>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.</para> - </entry> - </row> - <row> - <entry><constant>V4L2_EVENT_FRAME_SYNC</constant></entry> - <entry>4</entry> - <entry> - <para>Triggered immediately when the reception of a - frame has begun. This event has a - &v4l2-event-frame-sync; associated with it.</para> - - <para>If the hardware needs to be stopped in the case of a - buffer underrun it might not be able to generate this event. - In such cases the <structfield>frame_sequence</structfield> - field in &v4l2-event-frame-sync; will not be incremented. This - causes two consecutive frame sequence numbers to have n times - frame interval in between them.</para> - </entry> - </row> - <row> - <entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry> - <entry>0x08000000</entry> - <entry>Base event number for driver-private events.</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> |