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Hans Verkuil
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Mauro Carvalho Chehab
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Sep 26, 2012
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trunk/Documentation/DocBook/media/v4l/vidioc-subdev-g-edid.xml
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<refentry id="vidioc-subdev-g-edid"> | ||
<refmeta> | ||
<refentrytitle>ioctl VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID</refentrytitle> | ||
&manvol; | ||
</refmeta> | ||
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<refnamediv> | ||
<refname>VIDIOC_SUBDEV_G_EDID</refname> | ||
<refname>VIDIOC_SUBDEV_S_EDID</refname> | ||
<refpurpose>Get or set the EDID of a video receiver/transmitter</refpurpose> | ||
</refnamediv> | ||
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<refsynopsisdiv> | ||
<funcsynopsis> | ||
<funcprototype> | ||
<funcdef>int <function>ioctl</function></funcdef> | ||
<paramdef>int <parameter>fd</parameter></paramdef> | ||
<paramdef>int <parameter>request</parameter></paramdef> | ||
<paramdef>struct v4l2_subdev_edid *<parameter>argp</parameter></paramdef> | ||
</funcprototype> | ||
</funcsynopsis> | ||
<funcsynopsis> | ||
<funcprototype> | ||
<funcdef>int <function>ioctl</function></funcdef> | ||
<paramdef>int <parameter>fd</parameter></paramdef> | ||
<paramdef>int <parameter>request</parameter></paramdef> | ||
<paramdef>const struct v4l2_subdev_edid *<parameter>argp</parameter></paramdef> | ||
</funcprototype> | ||
</funcsynopsis> | ||
</refsynopsisdiv> | ||
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<refsect1> | ||
<title>Arguments</title> | ||
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<variablelist> | ||
<varlistentry> | ||
<term><parameter>fd</parameter></term> | ||
<listitem> | ||
<para>&fd;</para> | ||
</listitem> | ||
</varlistentry> | ||
<varlistentry> | ||
<term><parameter>request</parameter></term> | ||
<listitem> | ||
<para>VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID</para> | ||
</listitem> | ||
</varlistentry> | ||
<varlistentry> | ||
<term><parameter>argp</parameter></term> | ||
<listitem> | ||
<para></para> | ||
</listitem> | ||
</varlistentry> | ||
</variablelist> | ||
</refsect1> | ||
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<refsect1> | ||
<title>Description</title> | ||
<para>These ioctls can be used to get or set an EDID associated with an input pad | ||
from a receiver or an output pad of a transmitter subdevice.</para> | ||
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<para>To get the EDID data the application has to fill in the <structfield>pad</structfield>, | ||
<structfield>start_block</structfield>, <structfield>blocks</structfield> and <structfield>edid</structfield> | ||
fields and call <constant>VIDIOC_SUBDEV_G_EDID</constant>. The current EDID from block | ||
<structfield>start_block</structfield> and of size <structfield>blocks</structfield> | ||
will be placed in the memory <structfield>edid</structfield> points to. The <structfield>edid</structfield> | ||
pointer must point to memory at least <structfield>blocks</structfield> * 128 bytes | ||
large (the size of one block is 128 bytes).</para> | ||
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<para>If there are fewer blocks than specified, then the driver will set <structfield>blocks</structfield> | ||
to the actual number of blocks. If there are no EDID blocks available at all, then the error code | ||
ENODATA is set.</para> | ||
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<para>If blocks have to be retrieved from the sink, then this call will block until they | ||
have been read.</para> | ||
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<para>To set the EDID blocks of a receiver the application has to fill in the <structfield>pad</structfield>, | ||
<structfield>blocks</structfield> and <structfield>edid</structfield> fields and set | ||
<structfield>start_block</structfield> to 0. It is not possible to set part of an EDID, | ||
it is always all or nothing. Setting the EDID data is only valid for receivers as it makes | ||
no sense for a transmitter.</para> | ||
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<para>The driver assumes that the full EDID is passed in. If there are more EDID blocks than | ||
the hardware can handle then the EDID is not written, but instead the error code E2BIG is set | ||
and <structfield>blocks</structfield> is set to the maximum that the hardware supports. | ||
If <structfield>start_block</structfield> is any | ||
value other than 0 then the error code EINVAL is set.</para> | ||
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<para>To disable an EDID you set <structfield>blocks</structfield> to 0. Depending on the | ||
hardware this will drive the hotplug pin low and/or block the source from reading the EDID | ||
data in some way. In any case, the end result is the same: the EDID is no longer available. | ||
</para> | ||
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<table pgwide="1" frame="none" id="v4l2-subdev-edid"> | ||
<title>struct <structname>v4l2_subdev_edid</structname></title> | ||
<tgroup cols="3"> | ||
&cs-str; | ||
<tbody valign="top"> | ||
<row> | ||
<entry>__u32</entry> | ||
<entry><structfield>pad</structfield></entry> | ||
<entry>Pad for which to get/set the EDID blocks.</entry> | ||
</row> | ||
<row> | ||
<entry>__u32</entry> | ||
<entry><structfield>start_block</structfield></entry> | ||
<entry>Read the EDID from starting with this block. Must be 0 when setting | ||
the EDID.</entry> | ||
</row> | ||
<row> | ||
<entry>__u32</entry> | ||
<entry><structfield>blocks</structfield></entry> | ||
<entry>The number of blocks to get or set. Must be less or equal to 256 (the | ||
maximum number of blocks as defined by the standard). When you set the EDID and | ||
<structfield>blocks</structfield> is 0, then the EDID is disabled or erased.</entry> | ||
</row> | ||
<row> | ||
<entry>__u8 *</entry> | ||
<entry><structfield>edid</structfield></entry> | ||
<entry>Pointer to memory that contains the EDID. The minimum size is | ||
<structfield>blocks</structfield> * 128.</entry> | ||
</row> | ||
<row> | ||
<entry>__u32</entry> | ||
<entry><structfield>reserved</structfield>[5]</entry> | ||
<entry>Reserved for future extensions. Applications and drivers must | ||
set the array to zero.</entry> | ||
</row> | ||
</tbody> | ||
</tgroup> | ||
</table> | ||
</refsect1> | ||
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<refsect1> | ||
&return-value; | ||
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<variablelist> | ||
<varlistentry> | ||
<term><errorcode>ENODATA</errorcode></term> | ||
<listitem> | ||
<para>The EDID data is not available.</para> | ||
</listitem> | ||
</varlistentry> | ||
<varlistentry> | ||
<term><errorcode>E2BIG</errorcode></term> | ||
<listitem> | ||
<para>The EDID data you provided is more than the hardware can handle.</para> | ||
</listitem> | ||
</varlistentry> | ||
</variablelist> | ||
</refsect1> | ||
</refentry> |