Documentation/DocBook/media/v4l/cec-ioc-adap-g-phys-addr.xml

<refentry id="cec-ioc-adap-g-phys-addr">
  <refmeta>
    <refentrytitle>ioctl CEC_ADAP_G_PHYS_ADDR, CEC_ADAP_S_PHYS_ADDR</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>CEC_ADAP_G_PHYS_ADDR</refname>
    <refname>CEC_ADAP_S_PHYS_ADDR</refname>
    <refpurpose>Get or set the physical address</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
	<paramdef>__u16 *<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_ADAP_G_PHYS_ADDR, CEC_ADAP_S_PHYS_ADDR</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>To query the current physical address applications call the
<constant>CEC_ADAP_G_PHYS_ADDR</constant> ioctl with a pointer to an __u16
where the driver stores the physical address.</para>

    <para>To set a new physical address applications store the physical address in
an __u16 and call the <constant>CEC_ADAP_S_PHYS_ADDR</constant> ioctl with a
pointer to this integer. <constant>CEC_ADAP_S_PHYS_ADDR</constant> is only
available if <constant>CEC_CAP_PHYS_ADDR</constant> is set (&ENOTTY; will be returned
otherwise). <constant>CEC_ADAP_S_PHYS_ADDR</constant>
can only be called by a file handle in initiator mode (see &CEC-S-MODE;), if not
&EBUSY; will be returned.</para>

    <para>The physical address is a 16-bit number where each group of 4 bits
represent a digit of the physical address a.b.c.d where the most significant
4 bits represent 'a'. The CEC root device (usually the TV) has address 0.0.0.0.
Every device that is hooked up to an input of the TV has address a.0.0.0 (where
'a' is &ge; 1), devices hooked up to those in turn have addresses a.b.0.0, etc.
So a topology of up to 5 devices deep is supported. The physical address a
device shall use is stored in the EDID of the sink.</para>

<para>For example, the EDID for each HDMI input of the TV will have a different
physical address of the form a.0.0.0 that the sources will read out and use as
their physical address.</para>
  </refsect1>

  <refsect1>
    &return-value;
  </refsect1>
</refentry>