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Diffstat (limited to 'Documentation/DocBook/media/v4l/vidioc-dqevent.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/vidioc-dqevent.xml | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml new file mode 100644 index 0000000..e8714aa --- /dev/null +++ b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml @@ -0,0 +1,271 @@ +<refentry id="vidioc-dqevent"> + <refmeta> + <refentrytitle>ioctl VIDIOC_DQEVENT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_DQEVENT</refname> + <refpurpose>Dequeue 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 +*<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_DQEVENT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>Dequeue an event from a video device. No input is required + for this ioctl. All the fields of the &v4l2-event; structure are + filled by the driver. The file handle will also receive exceptions + which the application may get by e.g. using the select system + call.</para> + + <table frame="none" pgwide="1" id="v4l2-event"> + <title>struct <structname>v4l2_event</structname></title> + <tgroup cols="4"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry></entry> + <entry>Type of the event.</entry> + </row> + <row> + <entry>union</entry> + <entry><structfield>u</structfield></entry> + <entry></entry> + <entry></entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-event-vsync;</entry> + <entry><structfield>vsync</structfield></entry> + <entry>Event data for event V4L2_EVENT_VSYNC. + </entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-event-ctrl;</entry> + <entry><structfield>ctrl</structfield></entry> + <entry>Event data for event V4L2_EVENT_CTRL. + </entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-event-frame-sync;</entry> + <entry><structfield>frame</structfield></entry> + <entry>Event data for event V4L2_EVENT_FRAME_SYNC.</entry> + </row> + <row> + <entry></entry> + <entry>__u8</entry> + <entry><structfield>data</structfield>[64]</entry> + <entry>Event data. Defined by the event type. The union + should be used to define easily accessible type for + events.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>pending</structfield></entry> + <entry></entry> + <entry>Number of pending events excluding this one.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>sequence</structfield></entry> + <entry></entry> + <entry>Event sequence number. The sequence number is + incremented for every subscribed event that takes place. + If sequence numbers are not contiguous it means that + events have been lost. + </entry> + </row> + <row> + <entry>struct timespec</entry> + <entry><structfield>timestamp</structfield></entry> + <entry></entry> + <entry>Event timestamp.</entry> + </row> + <row> + <entry>u32</entry> + <entry><structfield>id</structfield></entry> + <entry></entry> + <entry>The ID associated with the event source. If the event does not + have an associated ID (this depends on the event type), then this + is 0.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[8]</entry> + <entry></entry> + <entry>Reserved for future extensions. Drivers must set + the array to zero.</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 frame="none" pgwide="1" id="v4l2-event-frame-sync"> + <title>struct <structname>v4l2_event_frame_sync</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>frame_sequence</structfield></entry> + <entry> + The sequence number of the frame being received. + </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> + <refsect1> + &return-value; + </refsect1> +</refentry> |