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Diffstat (limited to 'Documentation/DocBook/media/v4l/cec-ioc-dqevent.xml')
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diff --git a/Documentation/DocBook/media/v4l/cec-ioc-dqevent.xml b/Documentation/DocBook/media/v4l/cec-ioc-dqevent.xml new file mode 100644 index 000000000000..697dde575cd4 --- /dev/null +++ b/Documentation/DocBook/media/v4l/cec-ioc-dqevent.xml @@ -0,0 +1,202 @@ +<refentry id="cec-ioc-g-event"> + <refmeta> + <refentrytitle>ioctl CEC_DQEVENT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>CEC_DQEVENT</refname> + <refpurpose>Dequeue a CEC 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 cec_event *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>File descriptor returned by + <link linkend='cec-func-open'><function>open()</function></link>.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>CEC_DQEVENT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para> + Note: this documents the proposed CEC API. This API is not yet finalized and + is currently only available as a staging kernel module. + </para> + + <para>CEC devices can send asynchronous events. These can be retrieved by calling + the <constant>CEC_DQEVENT</constant> ioctl. If the file descriptor is in non-blocking + mode and no event is pending, then it will return -1 and set errno to the &EAGAIN;.</para> + + <para>The internal event queues are per-filehandle and per-event type. If there is + no more room in a queue then the last event is overwritten with the new one. This + means that intermediate results can be thrown away but that the latest event is always + available. This also means that is it possible to read two successive events that have + the same value (e.g. two CEC_EVENT_STATE_CHANGE events with the same state). In that + case the intermediate state changes were lost but it is guaranteed that the state + did change in between the two events.</para> + + <table pgwide="1" frame="none" id="cec-event-state-change"> + <title>struct <structname>cec_event_state_change</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u16</entry> + <entry><structfield>phys_addr</structfield></entry> + <entry>The current physical address.</entry> + </row> + <row> + <entry>__u16</entry> + <entry><structfield>log_addr_mask</structfield></entry> + <entry>The current set of claimed logical addresses.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="cec-event-lost-msgs"> + <title>struct <structname>cec_event_lost_msgs</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>lost_msgs</structfield></entry> + <entry>Set to the number of lost messages since the filehandle + was opened or since the last time this event was dequeued for + this filehandle. The messages lost are the oldest messages. So + when a new message arrives and there is no more room, then the + oldest message is discarded to make room for the new one. The + internal size of the message queue guarantees that all messages + received in the last two seconds will be stored. Since messages + should be replied to within a second according to the CEC + specification, this is more than enough. + </entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="cec-event"> + <title>struct <structname>cec_event</structname></title> + <tgroup cols="4"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u64</entry> + <entry><structfield>ts</structfield></entry> + <entry>Timestamp of the event in ns.</entry> + <entry></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>event</structfield></entry> + <entry>The CEC event type, see <xref linkend="cec-events" />.</entry> + <entry></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>Event flags, see <xref linkend="cec-event-flags" />.</entry> + <entry></entry> + </row> + <row> + <entry>union</entry> + <entry>(anonymous)</entry> + <entry></entry> + <entry></entry> + </row> + <row> + <entry></entry> + <entry>struct cec_event_state_change</entry> + <entry><structfield>state_change</structfield></entry> + <entry>The new adapter state as sent by the <constant>CEC_EVENT_STATE_CHANGE</constant> + event.</entry> + </row> + <row> + <entry></entry> + <entry>struct cec_event_lost_msgs</entry> + <entry><structfield>lost_msgs</structfield></entry> + <entry>The number of lost messages as sent by the <constant>CEC_EVENT_LOST_MSGS</constant> + event.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="cec-events"> + <title>CEC Events Types</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>CEC_EVENT_STATE_CHANGE</constant></entry> + <entry>1</entry> + <entry>Generated when the CEC Adapter's state changes. When open() is + called an initial event will be generated for that filehandle with the + CEC Adapter's state at that time. + </entry> + </row> + <row> + <entry><constant>CEC_EVENT_LOST_MSGS</constant></entry> + <entry>2</entry> + <entry>Generated if one or more CEC messages were lost because the + application didn't dequeue CEC messages fast enough.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="cec-event-flags"> + <title>CEC Event Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>CEC_EVENT_FL_INITIAL_VALUE</constant></entry> + <entry>1</entry> + <entry>Set for the initial events that are generated when the device is + opened. See the table above for which events do this. This allows + applications to learn the initial state of the CEC adapter at open() + time.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + </refsect1> +</refentry> |