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Commit c7169ad5 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
Browse files

[media] DocBook/media: add CEC documentation 



Add DocBook documentation for the CEC API.

Signed-off-by: default avatarHans Verkuil <hansverk@cisco.com>
[k.debski@samsung.com: add documentation for passthrough mode]
[k.debski@samsung.com: minor fixes and change of reserved field sizes]
Signed-off-by: default avatarKamil Debski <kamil@wypas.org>
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent c51202d3

Documentation/DocBook/device-drivers.tmpl

+3 −0
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@@ -272,6 +272,9 @@ X!Isound/sound_firmware.c 
!Iinclude/media/media-devnode.h

!Iinclude/media/media-entity.h

    </sect1>

    <sect1><title>Consumer Electronics Control devices</title>

!Iinclude/media/cec-edid.h

    </sect1>



  </chapter>

Documentation/DocBook/media/Makefile

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@@ -64,6 +64,7 @@ IOCTLS = \ 
	$(shell perl -ne 'print "$$1 " if /\#define\s+([A-Z][^\s]+)\s+_IO/' $(srctree)/include/uapi/linux/dvb/net.h) \

	$(shell perl -ne 'print "$$1 " if /\#define\s+([^\s]+)\s+_IO/' $(srctree)/include/uapi/linux/dvb/video.h) \

	$(shell perl -ne 'print "$$1 " if /\#define\s+([^\s]+)\s+_IO/' $(srctree)/include/uapi/linux/media.h) \

	$(shell perl -ne 'print "$$1 " if /\#define\s+([^\s]+)\s+_IO/' $(srctree)/include/linux/cec.h) \

	$(shell perl -ne 'print "$$1 " if /\#define\s+([^\s]+)\s+_IO/' $(srctree)/include/uapi/linux/v4l2-subdev.h) \



DEFINES = \
@@ -100,6 +101,7 @@ STRUCTS = \ 
	$(shell perl -ne 'print "$$1 " if (/^struct\s+([^\s]+)\s+/ && !/_old/)' $(srctree)/include/uapi/linux/dvb/net.h) \

	$(shell perl -ne 'print "$$1 " if (/^struct\s+([^\s]+)\s+/)' $(srctree)/include/uapi/linux/dvb/video.h) \

	$(shell perl -ne 'print "$$1 " if /^struct\s+([^\s]+)\s+/' $(srctree)/include/uapi/linux/media.h) \

	$(shell perl -ne 'print "$$1 " if /^struct\s+([^\s]+)\s+/' $(srctree)/include/linux/cec.h) \

	$(shell perl -ne 'print "$$1 " if /^struct\s+([^\s]+)\s+/' $(srctree)/include/uapi/linux/v4l2-subdev.h) \

	$(shell perl -ne 'print "$$1 " if /^struct\s+([^\s]+)\s+/' $(srctree)/include/uapi/linux/v4l2-mediabus.h)

Documentation/DocBook/media/v4l/biblio.xml

+10 −0
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@@ -342,6 +342,16 @@ in the frequency range from 87,5 to 108,0 MHz</title> 
      <subtitle>Specification Version 1.4a</subtitle>

    </biblioentry>



    <biblioentry id="hdmi2">

      <abbrev>HDMI2</abbrev>

      <authorgroup>

	<corpauthor>HDMI Licensing LLC

(<ulink url="http://www.hdmi.org">http://www.hdmi.org</ulink>)</corpauthor>

      </authorgroup>

      <title>High-Definition Multimedia Interface</title>

      <subtitle>Specification Version 2.0</subtitle>

    </biblioentry>



    <biblioentry id="dp">

      <abbrev>DP</abbrev>

      <authorgroup>

Documentation/DocBook/media/v4l/cec-api.xml

0 → 100644
+75 −0
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<partinfo>

  <authorgroup>

    <author>

      <firstname>Hans</firstname>

      <surname>Verkuil</surname>

      <affiliation><address><email>hans.verkuil@cisco.com</email></address></affiliation>

      <contrib>Initial version.</contrib>

    </author>

  </authorgroup>

  <copyright>

    <year>2016</year>

    <holder>Hans Verkuil</holder>

  </copyright>



  <revhistory>

    <!-- Put document revisions here, newest first. -->

    <revision>

      <revnumber>1.0.0</revnumber>

      <date>2016-03-17</date>

      <authorinitials>hv</authorinitials>

      <revremark>Initial revision</revremark>

    </revision>

  </revhistory>

</partinfo>



<title>CEC API</title>



<chapter id="cec-api">

  <title>CEC: Consumer Electronics Control</title>



  <section id="cec-intro">

    <title>Introduction</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>HDMI connectors provide a single pin for use by the Consumer Electronics

    Control protocol. This protocol allows different devices connected by an HDMI cable

    to communicate. The protocol for CEC version 1.4 is defined in supplements 1 (CEC)

    and 2 (HEAC or HDMI Ethernet and Audio Return Channel) of the HDMI 1.4a

    (<xref linkend="hdmi" />) specification and the extensions added to CEC version 2.0

    are defined in chapter 11 of the HDMI 2.0 (<xref linkend="hdmi2" />) specification.

    </para>



    <para>The bitrate is very slow (effectively no more than 36 bytes per second) and

    is based on the ancient AV.link protocol used in old SCART connectors. The protocol

    closely resembles a crazy Rube Goldberg contraption and is an unholy mix of low and

    high level messages. Some messages, especially those part of the HEAC protocol layered

    on top of CEC, need to be handled by the kernel, others can be handled either by the

    kernel or by userspace.</para>



    <para>In addition, CEC can be implemented in HDMI receivers, transmitters and in USB

    devices that have an HDMI input and an HDMI output and that control just the CEC pin.</para>



    <para>Drivers that support CEC will create a CEC device node (/dev/cecX)

    to give userspace access to the CEC adapter. The &CEC-ADAP-G-CAPS; ioctl will tell userspace

    what it is allowed to do.</para>

  </section>

</chapter>



<appendix id="cec-user-func">

  <title>Function Reference</title>

  <!-- Keep this alphabetically sorted. -->

  &sub-cec-func-open;

  &sub-cec-func-close;

  &sub-cec-func-ioctl;

  &sub-cec-func-poll;

  <!-- All ioctls go here. -->

  &sub-cec-ioc-adap-g-caps;

  &sub-cec-ioc-adap-g-log-addrs;

  &sub-cec-ioc-adap-g-phys-addr;

  &sub-cec-ioc-dqevent;

  &sub-cec-ioc-g-mode;

  &sub-cec-ioc-receive;

</appendix>

Documentation/DocBook/media/v4l/cec-func-close.xml

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<refentry id="cec-func-close">

  <refmeta>

    <refentrytitle>cec close()</refentrytitle>

    &manvol;

  </refmeta>



  <refnamediv>

    <refname>cec-close</refname>

    <refpurpose>Close a cec device</refpurpose>

  </refnamediv>



  <refsynopsisdiv>

    <funcsynopsis>

      <funcsynopsisinfo>#include &lt;unistd.h&gt;</funcsynopsisinfo>

      <funcprototype>

	<funcdef>int <function>close</function></funcdef>

	<paramdef>int <parameter>fd</parameter></paramdef>

      </funcprototype>

    </funcsynopsis>

  </refsynopsisdiv>



  <refsect1>

    <title>Arguments</title>



    <variablelist>

      <varlistentry>

	<term><parameter>fd</parameter></term>

	<listitem>

	  <para>&fd;</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>Closes the cec device. Resources associated with the file descriptor

    are freed. The device configuration remain unchanged.</para>

  </refsect1>



  <refsect1>

    <title>Return Value</title>



    <para><function>close</function> returns 0 on success. On error, -1 is

    returned, and <varname>errno</varname> is set appropriately. Possible error

    codes are:</para>



    <variablelist>

      <varlistentry>

	<term><errorcode>EBADF</errorcode></term>

	<listitem>

	  <para><parameter>fd</parameter> is not a valid open file descriptor.

	  </para>

	</listitem>

      </varlistentry>

    </variablelist>

  </refsect1>

</refentry>