mirror of https://gitee.com/openkylin/linux.git
163 lines
6.3 KiB
XML
163 lines
6.3 KiB
XML
<refentry id="vidioc-g-edid">
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<refmeta>
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<refentrytitle>ioctl VIDIOC_G_EDID, VIDIOC_S_EDID</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>VIDIOC_G_EDID</refname>
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<refname>VIDIOC_S_EDID</refname>
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<refpurpose>Get or set the EDID of a video receiver/transmitter</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>ioctl</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>request</parameter></paramdef>
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<paramdef>struct v4l2_edid *<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>ioctl</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>request</parameter></paramdef>
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<paramdef>struct v4l2_edid *<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><parameter>fd</parameter></term>
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<listitem>
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<para>&fd;</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>request</parameter></term>
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<listitem>
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<para>VIDIOC_G_EDID, VIDIOC_S_EDID</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>argp</parameter></term>
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<listitem>
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<para></para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Description</title>
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<para>These ioctls can be used to get or set an EDID associated with an input
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from a receiver or an output of a transmitter device. They can be
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used with subdevice nodes (/dev/v4l-subdevX) or with video nodes (/dev/videoX).</para>
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<para>When used with video nodes the <structfield>pad</structfield> field represents the
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input (for video capture devices) or output (for video output devices) index as
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is returned by &VIDIOC-ENUMINPUT; and &VIDIOC-ENUMOUTPUT; respectively. When used
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with subdevice nodes the <structfield>pad</structfield> field represents the
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input or output pad of the subdevice. If there is no EDID support for the given
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<structfield>pad</structfield> value, then the &EINVAL; will be returned.</para>
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<para>To get the EDID data the application has to fill in the <structfield>pad</structfield>,
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<structfield>start_block</structfield>, <structfield>blocks</structfield> and <structfield>edid</structfield>
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fields and call <constant>VIDIOC_G_EDID</constant>. The current EDID from block
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<structfield>start_block</structfield> and of size <structfield>blocks</structfield>
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will be placed in the memory <structfield>edid</structfield> points to. The <structfield>edid</structfield>
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pointer must point to memory at least <structfield>blocks</structfield> * 128 bytes
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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>
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to the actual number of blocks. If there are no EDID blocks available at all, then the error code
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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
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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>,
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<structfield>blocks</structfield> and <structfield>edid</structfield> fields and set
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<structfield>start_block</structfield> to 0. It is not possible to set part of an EDID,
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it is always all or nothing. Setting the EDID data is only valid for receivers as it makes
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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
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the hardware can handle then the EDID is not written, but instead the error code E2BIG is set
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and <structfield>blocks</structfield> is set to the maximum that the hardware supports.
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If <structfield>start_block</structfield> is any
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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
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hardware this will drive the hotplug pin low and/or block the source from reading the EDID
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data in some way. In any case, the end result is the same: the EDID is no longer available.
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</para>
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<table pgwide="1" frame="none" id="v4l2-edid">
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<title>struct <structname>v4l2_edid</structname></title>
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<tgroup cols="3">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>pad</structfield></entry>
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<entry>Pad for which to get/set the EDID blocks. When used with a video device
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node the pad represents the input or output index as returned by
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&VIDIOC-ENUMINPUT; and &VIDIOC-ENUMOUTPUT; respectively.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>start_block</structfield></entry>
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<entry>Read the EDID from starting with this block. Must be 0 when setting
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the EDID.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>blocks</structfield></entry>
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<entry>The number of blocks to get or set. Must be less or equal to 256 (the
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maximum number of blocks as defined by the standard). When you set the EDID and
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<structfield>blocks</structfield> is 0, then the EDID is disabled or erased.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[5]</entry>
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<entry>Reserved for future extensions. Applications and drivers must
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set the array to zero.</entry>
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</row>
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<row>
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<entry>__u8 *</entry>
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<entry><structfield>edid</structfield></entry>
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<entry>Pointer to memory that contains the EDID. The minimum size is
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<structfield>blocks</structfield> * 128.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</refsect1>
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<refsect1>
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&return-value;
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<variablelist>
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<varlistentry>
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<term><errorcode>ENODATA</errorcode></term>
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<listitem>
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<para>The EDID data is not available.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><errorcode>E2BIG</errorcode></term>
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<listitem>
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<para>The EDID data you provided is more than the hardware can handle.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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</refentry>
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