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SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: V4L3 4.. _VIDIOC_G_EDID:5 6******************************************************************************7ioctl VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID8******************************************************************************9 10Name11====12 13VIDIOC_G_EDID - VIDIOC_S_EDID - VIDIOC_SUBDEV_G_EDID - VIDIOC_SUBDEV_S_EDID - Get or set the EDID of a video receiver/transmitter14 15Synopsis16========17 18.. c:macro:: VIDIOC_G_EDID19 20``int ioctl(int fd, VIDIOC_G_EDID, struct v4l2_edid *argp)``21 22.. c:macro:: VIDIOC_S_EDID23 24``int ioctl(int fd, VIDIOC_S_EDID, struct v4l2_edid *argp)``25 26.. c:macro:: VIDIOC_SUBDEV_G_EDID27 28``int ioctl(int fd, VIDIOC_SUBDEV_G_EDID, struct v4l2_edid *argp)``29 30.. c:macro:: VIDIOC_SUBDEV_S_EDID31 32``int ioctl(int fd, VIDIOC_SUBDEV_S_EDID, struct v4l2_edid *argp)``33 34Arguments35=========36 37``fd``38 File descriptor returned by :c:func:`open()`.39 40``argp``41 Pointer to struct :c:type:`v4l2_edid`.42 43Description44===========45 46These ioctls can be used to get or set an EDID associated with an input47from a receiver or an output of a transmitter device. They can be used48with subdevice nodes (/dev/v4l-subdevX) or with video nodes49(/dev/videoX).50 51When used with video nodes the ``pad`` field represents the input (for52video capture devices) or output (for video output devices) index as is53returned by :ref:`VIDIOC_ENUMINPUT` and54:ref:`VIDIOC_ENUMOUTPUT` respectively. When used55with subdevice nodes the ``pad`` field represents the input or output56pad of the subdevice. If there is no EDID support for the given ``pad``57value, then the ``EINVAL`` error code will be returned.58 59To get the EDID data the application has to fill in the ``pad``,60``start_block``, ``blocks`` and ``edid`` fields, zero the ``reserved``61array and call :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>`. The current EDID from block62``start_block`` and of size ``blocks`` will be placed in the memory63``edid`` points to. The ``edid`` pointer must point to memory at least64``blocks`` * 128 bytes large (the size of one block is 128 bytes).65 66If there are fewer blocks than specified, then the driver will set67``blocks`` to the actual number of blocks. If there are no EDID blocks68available at all, then the error code ``ENODATA`` is set.69 70If blocks have to be retrieved from the sink, then this call will block71until they have been read.72 73If ``start_block`` and ``blocks`` are both set to 0 when74:ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the75total number of available EDID blocks and it will return 0 without76copying any data. This is an easy way to discover how many EDID blocks77there are.78 79.. note::80 81 If there are no EDID blocks available at all, then82 the driver will set ``blocks`` to 0 and it returns 0.83 84To set the EDID blocks of a receiver the application has to fill in the85``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and86zero the ``reserved`` array. It is not possible to set part of an EDID,87it is always all or nothing. Setting the EDID data is only valid for88receivers as it makes no sense for a transmitter.89 90The driver assumes that the full EDID is passed in. If there are more91EDID blocks than the hardware can handle then the EDID is not written,92but instead the error code ``E2BIG`` is set and ``blocks`` is set to the93maximum that the hardware supports. If ``start_block`` is any value94other than 0 then the error code ``EINVAL`` is set.95 96To disable an EDID you set ``blocks`` to 0. Depending on the hardware97this will drive the hotplug pin low and/or block the source from reading98the EDID data in some way. In any case, the end result is the same: the99EDID is no longer available.100 101.. c:type:: v4l2_edid102 103.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|104 105.. flat-table:: struct v4l2_edid106 :header-rows: 0107 :stub-columns: 0108 :widths: 1 1 2109 110 * - __u32111 - ``pad``112 - Pad for which to get/set the EDID blocks. When used with a video113 device node the pad represents the input or output index as114 returned by :ref:`VIDIOC_ENUMINPUT` and115 :ref:`VIDIOC_ENUMOUTPUT` respectively.116 * - __u32117 - ``start_block``118 - Read the EDID from starting with this block. Must be 0 when119 setting the EDID.120 * - __u32121 - ``blocks``122 - The number of blocks to get or set. Must be less or equal to 256123 (the maximum number of blocks as defined by the standard). When124 you set the EDID and ``blocks`` is 0, then the EDID is disabled or125 erased.126 * - __u32127 - ``reserved``\ [5]128 - Reserved for future extensions. Applications and drivers must set129 the array to zero.130 * - __u8 *131 - ``edid``132 - Pointer to memory that contains the EDID. The minimum size is133 ``blocks`` * 128.134 135Return Value136============137 138On success 0 is returned, on error -1 and the ``errno`` variable is set139appropriately. The generic error codes are described at the140:ref:`Generic Error Codes <gen-errors>` chapter.141 142``ENODATA``143 The EDID data is not available.144 145``E2BIG``146 The EDID data you provided is more than the hardware can handle.147