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authorSakari Ailus <sakari.ailus@maxwell.research.nokia.com>2010-03-27 13:58:24 (GMT)
committerMauro Carvalho Chehab <mchehab@redhat.com>2010-05-19 15:58:07 (GMT)
commitdd96608369be9d3cfc604eaa3a53a2d38f1cb415 (patch)
treefc3e9f5f70aef35255fd2cca2e5a88498827d093 /Documentation/DocBook
parentd3d7c963562adad92e968df23c425ae964fe9ce2 (diff)
V4L/DVB: V4L: Events: Add documentation
Add documentation on how to use V4L2 events, both for V4L2 drivers and for V4L2 applications. Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook')
-rw-r--r--Documentation/DocBook/media-entities.tmpl9
-rw-r--r--Documentation/DocBook/v4l/dev-event.xml31
-rw-r--r--Documentation/DocBook/v4l/v4l2.xml3
-rw-r--r--Documentation/DocBook/v4l/vidioc-dqevent.xml124
-rw-r--r--Documentation/DocBook/v4l/vidioc-subscribe-event.xml104
5 files changed, 271 insertions, 0 deletions
diff --git a/Documentation/DocBook/media-entities.tmpl b/Documentation/DocBook/media-entities.tmpl
index c725cb8..770be3c 100644
--- a/Documentation/DocBook/media-entities.tmpl
+++ b/Documentation/DocBook/media-entities.tmpl
@@ -17,6 +17,7 @@
<!ENTITY VIDIOC-DBG-G-REGISTER "<link linkend='vidioc-dbg-g-register'><constant>VIDIOC_DBG_G_REGISTER</constant></link>">
<!ENTITY VIDIOC-DBG-S-REGISTER "<link linkend='vidioc-dbg-g-register'><constant>VIDIOC_DBG_S_REGISTER</constant></link>">
<!ENTITY VIDIOC-DQBUF "<link linkend='vidioc-qbuf'><constant>VIDIOC_DQBUF</constant></link>">
+<!ENTITY VIDIOC-DQEVENT "<link linkend='vidioc-dqevent'><constant>VIDIOC_DQEVENT</constant></link>">
<!ENTITY VIDIOC-ENCODER-CMD "<link linkend='vidioc-encoder-cmd'><constant>VIDIOC_ENCODER_CMD</constant></link>">
<!ENTITY VIDIOC-ENUMAUDIO "<link linkend='vidioc-enumaudio'><constant>VIDIOC_ENUMAUDIO</constant></link>">
<!ENTITY VIDIOC-ENUMAUDOUT "<link linkend='vidioc-enumaudioout'><constant>VIDIOC_ENUMAUDOUT</constant></link>">
@@ -60,6 +61,7 @@
<!ENTITY VIDIOC-REQBUFS "<link linkend='vidioc-reqbufs'><constant>VIDIOC_REQBUFS</constant></link>">
<!ENTITY VIDIOC-STREAMOFF "<link linkend='vidioc-streamon'><constant>VIDIOC_STREAMOFF</constant></link>">
<!ENTITY VIDIOC-STREAMON "<link linkend='vidioc-streamon'><constant>VIDIOC_STREAMON</constant></link>">
+<!ENTITY VIDIOC-SUBSCRIBE-EVENT "<link linkend='vidioc-subscribe-event'><constant>VIDIOC_SUBSCRIBE_EVENT</constant></link>">
<!ENTITY VIDIOC-S-AUDIO "<link linkend='vidioc-g-audio'><constant>VIDIOC_S_AUDIO</constant></link>">
<!ENTITY VIDIOC-S-AUDOUT "<link linkend='vidioc-g-audioout'><constant>VIDIOC_S_AUDOUT</constant></link>">
<!ENTITY VIDIOC-S-CROP "<link linkend='vidioc-g-crop'><constant>VIDIOC_S_CROP</constant></link>">
@@ -141,6 +143,8 @@
<!ENTITY v4l2-enc-idx "struct&nbsp;<link linkend='v4l2-enc-idx'>v4l2_enc_idx</link>">
<!ENTITY v4l2-enc-idx-entry "struct&nbsp;<link linkend='v4l2-enc-idx-entry'>v4l2_enc_idx_entry</link>">
<!ENTITY v4l2-encoder-cmd "struct&nbsp;<link linkend='v4l2-encoder-cmd'>v4l2_encoder_cmd</link>">
+<!ENTITY v4l2-event "struct&nbsp;<link linkend='v4l2-event'>v4l2_event</link>">
+<!ENTITY v4l2-event-subscription "struct&nbsp;<link linkend='v4l2-event-subscription'>v4l2_event_subscription</link>">
<!ENTITY v4l2-ext-control "struct&nbsp;<link linkend='v4l2-ext-control'>v4l2_ext_control</link>">
<!ENTITY v4l2-ext-controls "struct&nbsp;<link linkend='v4l2-ext-controls'>v4l2_ext_controls</link>">
<!ENTITY v4l2-fmtdesc "struct&nbsp;<link linkend='v4l2-fmtdesc'>v4l2_fmtdesc</link>">
@@ -200,6 +204,7 @@
<!ENTITY sub-controls SYSTEM "v4l/controls.xml">
<!ENTITY sub-dev-capture SYSTEM "v4l/dev-capture.xml">
<!ENTITY sub-dev-codec SYSTEM "v4l/dev-codec.xml">
+<!ENTITY sub-dev-event SYSTEM "v4l/dev-event.xml">
<!ENTITY sub-dev-effect SYSTEM "v4l/dev-effect.xml">
<!ENTITY sub-dev-osd SYSTEM "v4l/dev-osd.xml">
<!ENTITY sub-dev-output SYSTEM "v4l/dev-output.xml">
@@ -292,6 +297,8 @@
<!ENTITY sub-v4l2grab-c SYSTEM "v4l/v4l2grab.c.xml">
<!ENTITY sub-videodev2-h SYSTEM "v4l/videodev2.h.xml">
<!ENTITY sub-v4l2 SYSTEM "v4l/v4l2.xml">
+<!ENTITY sub-dqevent SYSTEM "v4l/vidioc-dqevent.xml">
+<!ENTITY sub-subscribe-event SYSTEM "v4l/vidioc-subscribe-event.xml">
<!ENTITY sub-intro SYSTEM "dvb/intro.xml">
<!ENTITY sub-frontend SYSTEM "dvb/frontend.xml">
<!ENTITY sub-dvbproperty SYSTEM "dvb/dvbproperty.xml">
@@ -381,3 +388,5 @@
<!ENTITY reqbufs SYSTEM "v4l/vidioc-reqbufs.xml">
<!ENTITY s-hw-freq-seek SYSTEM "v4l/vidioc-s-hw-freq-seek.xml">
<!ENTITY streamon SYSTEM "v4l/vidioc-streamon.xml">
+<!ENTITY dqevent SYSTEM "v4l/vidioc-dqevent.xml">
+<!ENTITY subscribe_event SYSTEM "v4l/vidioc-subscribe-event.xml">
diff --git a/Documentation/DocBook/v4l/dev-event.xml b/Documentation/DocBook/v4l/dev-event.xml
new file mode 100644
index 0000000..be5a98f
--- /dev/null
+++ b/Documentation/DocBook/v4l/dev-event.xml
@@ -0,0 +1,31 @@
+ <title>Event Interface</title>
+
+ <para>The V4L2 event interface provides means for user to get
+ immediately notified on certain conditions taking place on a device.
+ This might include start of frame or loss of signal events, for
+ example.
+ </para>
+
+ <para>To receive events, the events the user is interested in first must
+ be subscribed using the &VIDIOC-SUBSCRIBE-EVENT; ioctl. Once an event is
+ subscribed, the events of subscribed types are dequeueable using the
+ &VIDIOC-DQEVENT; ioctl. Events may be unsubscribed using
+ VIDIOC_UNSUBSCRIBE_EVENT ioctl. The special event type V4L2_EVENT_ALL may
+ be used to unsubscribe all the events the driver supports.</para>
+
+ <para>The event subscriptions and event queues are specific to file
+ handles. Subscribing an event on one file handle does not affect
+ other file handles.
+ </para>
+
+ <para>The information on dequeueable events is obtained by using select or
+ poll system calls on video devices. The V4L2 events use POLLPRI events on
+ poll system call and exceptions on select system call. </para>
+
+ <!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+ -->
diff --git a/Documentation/DocBook/v4l/v4l2.xml b/Documentation/DocBook/v4l/v4l2.xml
index 060105a..9737243 100644
--- a/Documentation/DocBook/v4l/v4l2.xml
+++ b/Documentation/DocBook/v4l/v4l2.xml
@@ -401,6 +401,7 @@ and discussions on the V4L mailing list.</revremark>
<section id="ttx"> &sub-dev-teletext; </section>
<section id="radio"> &sub-dev-radio; </section>
<section id="rds"> &sub-dev-rds; </section>
+ <section id="event"> &sub-dev-event; </section>
</chapter>
<chapter id="driver">
@@ -426,6 +427,7 @@ and discussions on the V4L mailing list.</revremark>
&sub-cropcap;
&sub-dbg-g-chip-ident;
&sub-dbg-g-register;
+ &sub-dqevent;
&sub-encoder-cmd;
&sub-enumaudio;
&sub-enumaudioout;
@@ -467,6 +469,7 @@ and discussions on the V4L mailing list.</revremark>
&sub-reqbufs;
&sub-s-hw-freq-seek;
&sub-streamon;
+ &sub-subscribe-event;
<!-- End of ioctls. -->
&sub-mmap;
&sub-munmap;
diff --git a/Documentation/DocBook/v4l/vidioc-dqevent.xml b/Documentation/DocBook/v4l/vidioc-dqevent.xml
new file mode 100644
index 0000000..eb45c16
--- /dev/null
+++ b/Documentation/DocBook/v4l/vidioc-dqevent.xml
@@ -0,0 +1,124 @@
+<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>__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 timeval</entry>
+ <entry><structfield>timestamp</structfield></entry>
+ <entry></entry>
+ <entry>Event timestamp.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>reserved</structfield>[9]</entry>
+ <entry></entry>
+ <entry>Reserved for future extensions. Drivers must set
+ the array to zero.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ </refsect1>
+</refentry>
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->
diff --git a/Documentation/DocBook/v4l/vidioc-subscribe-event.xml b/Documentation/DocBook/v4l/vidioc-subscribe-event.xml
new file mode 100644
index 0000000..71ab88c
--- /dev/null
+++ b/Documentation/DocBook/v4l/vidioc-subscribe-event.xml
@@ -0,0 +1,104 @@
+<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>reserved</structfield>[7]</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_PRIVATE_START</constant></entry>
+ <entry>0x08000000</entry>
+ <entry>Base event number for driver-private events.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ </refsect1>
+</refentry>
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->

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