Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.
1 <refentry id="vidioc-g-edid"> 2 <refmeta> 3 <refentrytitle>ioctl VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID</refentrytitle> 4 &manvol; 5 </refmeta> 6 7 <refnamediv> 8 <refname>VIDIOC_G_EDID</refname> 9 <refname>VIDIOC_S_EDID</refname> 10 <refname>VIDIOC_SUBDEV_G_EDID</refname> 11 <refname>VIDIOC_SUBDEV_S_EDID</refname> 12 <refpurpose>Get or set the EDID of a video receiver/transmitter</refpurpose> 13 </refnamediv> 14 15 <refsynopsisdiv> 16 <funcsynopsis> 17 <funcprototype> 18 <funcdef>int <function>ioctl</function></funcdef> 19 <paramdef>int <parameter>fd</parameter></paramdef> 20 <paramdef>int <parameter>request</parameter></paramdef> 21 <paramdef>struct v4l2_edid *<parameter>argp</parameter></paramdef> 22 </funcprototype> 23 </funcsynopsis> 24 <funcsynopsis> 25 <funcprototype> 26 <funcdef>int <function>ioctl</function></funcdef> 27 <paramdef>int <parameter>fd</parameter></paramdef> 28 <paramdef>int <parameter>request</parameter></paramdef> 29 <paramdef>struct v4l2_edid *<parameter>argp</parameter></paramdef> 30 </funcprototype> 31 </funcsynopsis> 32 </refsynopsisdiv> 33 34 <refsect1> 35 <title>Arguments</title> 36 37 <variablelist> 38 <varlistentry> 39 <term><parameter>fd</parameter></term> 40 <listitem> 41 <para>&fd;</para> 42 </listitem> 43 </varlistentry> 44 <varlistentry> 45 <term><parameter>request</parameter></term> 46 <listitem> 47 <para>VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID</para> 48 </listitem> 49 </varlistentry> 50 <varlistentry> 51 <term><parameter>argp</parameter></term> 52 <listitem> 53 <para></para> 54 </listitem> 55 </varlistentry> 56 </variablelist> 57 </refsect1> 58 59 <refsect1> 60 <title>Description</title> 61 <para>These ioctls can be used to get or set an EDID associated with an input 62 from a receiver or an output of a transmitter device. They can be 63 used with subdevice nodes (/dev/v4l-subdevX) or with video nodes (/dev/videoX).</para> 64 65 <para>When used with video nodes the <structfield>pad</structfield> field represents the 66 input (for video capture devices) or output (for video output devices) index as 67 is returned by &VIDIOC-ENUMINPUT; and &VIDIOC-ENUMOUTPUT; respectively. When used 68 with subdevice nodes the <structfield>pad</structfield> field represents the 69 input or output pad of the subdevice. If there is no EDID support for the given 70 <structfield>pad</structfield> value, then the &EINVAL; will be returned.</para> 71 72 <para>To get the EDID data the application has to fill in the <structfield>pad</structfield>, 73 <structfield>start_block</structfield>, <structfield>blocks</structfield> and <structfield>edid</structfield> 74 fields, zero the <structfield>reserved</structfield> array and call 75 <constant>VIDIOC_G_EDID</constant>. The current EDID from block 76 <structfield>start_block</structfield> and of size <structfield>blocks</structfield> 77 will be placed in the memory <structfield>edid</structfield> points to. The <structfield>edid</structfield> 78 pointer must point to memory at least <structfield>blocks</structfield> * 128 bytes 79 large (the size of one block is 128 bytes).</para> 80 81 <para>If there are fewer blocks than specified, then the driver will set <structfield>blocks</structfield> 82 to the actual number of blocks. If there are no EDID blocks available at all, then the error code 83 ENODATA is set.</para> 84 85 <para>If blocks have to be retrieved from the sink, then this call will block until they 86 have been read.</para> 87 88 <para>If <structfield>start_block</structfield> and <structfield>blocks</structfield> are 89 both set to 0 when <constant>VIDIOC_G_EDID</constant> is called, then the driver will 90 set <structfield>blocks</structfield> to the total number of available EDID blocks 91 and it will return 0 without copying any data. This is an easy way to discover how many 92 EDID blocks there are. Note that if there are no EDID blocks available at all, then 93 the driver will set <structfield>blocks</structfield> to 0 and it returns 0.</para> 94 95 <para>To set the EDID blocks of a receiver the application has to fill in the <structfield>pad</structfield>, 96 <structfield>blocks</structfield> and <structfield>edid</structfield> fields, set 97 <structfield>start_block</structfield> to 0 and zero the <structfield>reserved</structfield> array. 98 It is not possible to set part of an EDID, 99 it is always all or nothing. Setting the EDID data is only valid for receivers as it makes 100 no sense for a transmitter.</para> 101 102 <para>The driver assumes that the full EDID is passed in. If there are more EDID blocks than 103 the hardware can handle then the EDID is not written, but instead the error code E2BIG is set 104 and <structfield>blocks</structfield> is set to the maximum that the hardware supports. 105 If <structfield>start_block</structfield> is any 106 value other than 0 then the error code EINVAL is set.</para> 107 108 <para>To disable an EDID you set <structfield>blocks</structfield> to 0. Depending on the 109 hardware this will drive the hotplug pin low and/or block the source from reading the EDID 110 data in some way. In any case, the end result is the same: the EDID is no longer available. 111 </para> 112 113 <table pgwide="1" frame="none" id="v4l2-edid"> 114 <title>struct <structname>v4l2_edid</structname></title> 115 <tgroup cols="3"> 116 &cs-str; 117 <tbody valign="top"> 118 <row> 119 <entry>__u32</entry> 120 <entry><structfield>pad</structfield></entry> 121 <entry>Pad for which to get/set the EDID blocks. When used with a video device 122 node the pad represents the input or output index as returned by 123 &VIDIOC-ENUMINPUT; and &VIDIOC-ENUMOUTPUT; respectively.</entry> 124 </row> 125 <row> 126 <entry>__u32</entry> 127 <entry><structfield>start_block</structfield></entry> 128 <entry>Read the EDID from starting with this block. Must be 0 when setting 129 the EDID.</entry> 130 </row> 131 <row> 132 <entry>__u32</entry> 133 <entry><structfield>blocks</structfield></entry> 134 <entry>The number of blocks to get or set. Must be less or equal to 256 (the 135 maximum number of blocks as defined by the standard). When you set the EDID and 136 <structfield>blocks</structfield> is 0, then the EDID is disabled or erased.</entry> 137 </row> 138 <row> 139 <entry>__u32</entry> 140 <entry><structfield>reserved</structfield>[5]</entry> 141 <entry>Reserved for future extensions. Applications and drivers must 142 set the array to zero.</entry> 143 </row> 144 <row> 145 <entry>__u8 *</entry> 146 <entry><structfield>edid</structfield></entry> 147 <entry>Pointer to memory that contains the EDID. The minimum size is 148 <structfield>blocks</structfield> * 128.</entry> 149 </row> 150 </tbody> 151 </tgroup> 152 </table> 153 </refsect1> 154 155 <refsect1> 156 &return-value; 157 158 <variablelist> 159 <varlistentry> 160 <term><errorcode>ENODATA</errorcode></term> 161 <listitem> 162 <para>The EDID data is not available.</para> 163 </listitem> 164 </varlistentry> 165 <varlistentry> 166 <term><errorcode>E2BIG</errorcode></term> 167 <listitem> 168 <para>The EDID data you provided is more than the hardware can handle.</para> 169 </listitem> 170 </varlistentry> 171 </variablelist> 172 </refsect1> 173 </refentry>
