Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 <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 &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>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 &v4l2-event-ctrl; associated with it. This struct
 		contains much of the same information as &v4l2-queryctrl; and
 		&v4l2-control;.

 		If the event is generated due to a call to &VIDIOC-S-CTRL; or
 		&VIDIOC-S-EXT-CTRLS;, then the event will not be sent to
 		the file handle that called the ioctl function. This prevents
 		nasty feedback loops.
 	    </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. Other events will ignore
 		this flag.</entry>
 	  </row>
 	</tbody>
       </tgroup>
     </table>

     <table frame="none" pgwide="1" id="v4l2-event-vsync">
       <title>struct <structname>v4l2_event_vsync</structname></title>
       <tgroup cols="3">
 	&cs-str;
 	<tbody valign="top">
 	  <row>
 	    <entry>__u8</entry>
 	    <entry><structfield>field</structfield></entry>
 	    <entry>The upcoming field. See &v4l2-field;.</entry>
 	  </row>
 	</tbody>
       </tgroup>
     </table>

     <table frame="none" pgwide="1" id="v4l2-event-ctrl">
       <title>struct <structname>v4l2_event_ctrl</structname></title>
       <tgroup cols="4">
 	&cs-str;
 	<tbody valign="top">
 	  <row>
 	    <entry>__u32</entry>
 	    <entry><structfield>changes</structfield></entry>
 	    <entry></entry>
 	    <entry>A bitmask that tells what has changed. See <xref linkend="changes-flags" />.</entry>
 	  </row>
 	  <row>
 	    <entry>__u32</entry>
 	    <entry><structfield>type</structfield></entry>
 	    <entry></entry>
 	    <entry>The type of the control. See &v4l2-ctrl-type;.</entry>
 	  </row>
 	  <row>
 	    <entry>union (anonymous)</entry>
 	    <entry></entry>
 	    <entry></entry>
 	    <entry></entry>
 	  </row>
 	  <row>
 	    <entry></entry>
 	    <entry>__s32</entry>
 	    <entry><structfield>value</structfield></entry>
 	    <entry>The 32-bit value of the control for 32-bit control types.
 		This is 0 for string controls since the value of a string
 		cannot be passed using &VIDIOC-DQEVENT;.</entry>
 	  </row>
 	  <row>
 	    <entry></entry>
 	    <entry>__s64</entry>
 	    <entry><structfield>value64</structfield></entry>
 	    <entry>The 64-bit value of the control for 64-bit control types.</entry>
 	  </row>
 	  <row>
 	    <entry>__u32</entry>
 	    <entry><structfield>flags</structfield></entry>
 	    <entry></entry>
 	    <entry>The control flags. See <xref linkend="control-flags" />.</entry>
 	  </row>
 	  <row>
 	    <entry>__s32</entry>
 	    <entry><structfield>minimum</structfield></entry>
 	    <entry></entry>
 	    <entry>The minimum value of the control. See &v4l2-queryctrl;.</entry>
 	  </row>
 	  <row>
 	    <entry>__s32</entry>
 	    <entry><structfield>maximum</structfield></entry>
 	    <entry></entry>
 	    <entry>The maximum value of the control. See &v4l2-queryctrl;.</entry>
 	  </row>
 	  <row>
 	    <entry>__s32</entry>
 	    <entry><structfield>step</structfield></entry>
 	    <entry></entry>
 	    <entry>The step value of the control. See &v4l2-queryctrl;.</entry>
 	  </row>
 	  <row>
 	    <entry>__s32</entry>
 	    <entry><structfield>default_value</structfield></entry>
 	    <entry></entry>
 	    <entry>The default value value of the control. See &v4l2-queryctrl;.</entry>
 	  </row>
 	</tbody>
       </tgroup>
     </table>

     <table pgwide="1" frame="none" id="changes-flags">
       <title>Changes</title>
       <tgroup cols="3">
 	&cs-def;
 	<tbody valign="top">
 	  <row>
 	    <entry><constant>V4L2_EVENT_CTRL_CH_VALUE</constant></entry>
 	    <entry>0x0001</entry>
 	    <entry>This control event was triggered because the value of the control
 		changed. Special case: if a button control is pressed, then this
 		event is sent as well, even though there is not explicit value
 		associated with a button control.</entry>
 	  </row>
 	  <row>
 	    <entry><constant>V4L2_EVENT_CTRL_CH_FLAGS</constant></entry>
 	    <entry>0x0002</entry>
 	    <entry>This control event was triggered because the control flags
 		changed.</entry>
 	  </row>
 	</tbody>
       </tgroup>
     </table>

   </refsect1>
 </refentry>
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	<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 &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>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 &v4l2-event-ctrl; associated with it. This struct
	contains much of the same information as &v4l2-queryctrl; and
	&v4l2-control;.

	If the event is generated due to a call to &VIDIOC-S-CTRL; or
	&VIDIOC-S-EXT-CTRLS;, then the event will not be sent to
	the file handle that called the ioctl function. This prevents
	nasty feedback loops.
	</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. Other events will ignore
	this flag.</entry>
	</row>
	</tbody>
	</tgroup>
	</table>

	<table frame="none" pgwide="1" id="v4l2-event-vsync">
	<title>struct <structname>v4l2_event_vsync</structname></title>
	<tgroup cols="3">
	&cs-str;
	<tbody valign="top">
	<row>
	<entry>__u8</entry>
	<entry><structfield>field</structfield></entry>
	<entry>The upcoming field. See &v4l2-field;.</entry>
	</row>
	</tbody>
	</tgroup>
	</table>

	<table frame="none" pgwide="1" id="v4l2-event-ctrl">
	<title>struct <structname>v4l2_event_ctrl</structname></title>
	<tgroup cols="4">
	&cs-str;
	<tbody valign="top">
	<row>
	<entry>__u32</entry>
	<entry><structfield>changes</structfield></entry>
	<entry></entry>
	<entry>A bitmask that tells what has changed. See <xref linkend="changes-flags" />.</entry>
	</row>
	<row>
	<entry>__u32</entry>
	<entry><structfield>type</structfield></entry>
	<entry></entry>
	<entry>The type of the control. See &v4l2-ctrl-type;.</entry>
	</row>
	<row>
	<entry>union (anonymous)</entry>
	<entry></entry>
	<entry></entry>
	<entry></entry>
	</row>
	<row>
	<entry></entry>
	<entry>__s32</entry>
	<entry><structfield>value</structfield></entry>
	<entry>The 32-bit value of the control for 32-bit control types.
	This is 0 for string controls since the value of a string
	cannot be passed using &VIDIOC-DQEVENT;.</entry>
	</row>
	<row>
	<entry></entry>
	<entry>__s64</entry>
	<entry><structfield>value64</structfield></entry>
	<entry>The 64-bit value of the control for 64-bit control types.</entry>
	</row>
	<row>
	<entry>__u32</entry>
	<entry><structfield>flags</structfield></entry>
	<entry></entry>
	<entry>The control flags. See <xref linkend="control-flags" />.</entry>
	</row>
	<row>
	<entry>__s32</entry>
	<entry><structfield>minimum</structfield></entry>
	<entry></entry>
	<entry>The minimum value of the control. See &v4l2-queryctrl;.</entry>
	</row>
	<row>
	<entry>__s32</entry>
	<entry><structfield>maximum</structfield></entry>
	<entry></entry>
	<entry>The maximum value of the control. See &v4l2-queryctrl;.</entry>
	</row>
	<row>
	<entry>__s32</entry>
	<entry><structfield>step</structfield></entry>
	<entry></entry>
	<entry>The step value of the control. See &v4l2-queryctrl;.</entry>
	</row>
	<row>
	<entry>__s32</entry>
	<entry><structfield>default_value</structfield></entry>
	<entry></entry>
	<entry>The default value value of the control. See &v4l2-queryctrl;.</entry>
	</row>
	</tbody>
	</tgroup>
	</table>

	<table pgwide="1" frame="none" id="changes-flags">
	<title>Changes</title>
	<tgroup cols="3">
	&cs-def;
	<tbody valign="top">
	<row>
	<entry><constant>V4L2_EVENT_CTRL_CH_VALUE</constant></entry>
	<entry>0x0001</entry>
	<entry>This control event was triggered because the value of the control
	changed. Special case: if a button control is pressed, then this
	event is sent as well, even though there is not explicit value
	associated with a button control.</entry>
	</row>
	<row>
	<entry><constant>V4L2_EVENT_CTRL_CH_FLAGS</constant></entry>
	<entry>0x0002</entry>
	<entry>This control event was triggered because the control flags
	changed.</entry>
	</row>
	</tbody>
	</tgroup>
	</table>

	</refsect1>
	</refentry>
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