147 lines
5.0 KiB
ReStructuredText
147 lines
5.0 KiB
ReStructuredText
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
|
|
.. c:namespace:: V4L
|
|
|
|
.. _VIDIOC_G_EDID:
|
|
|
|
******************************************************************************
|
|
ioctl VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID
|
|
******************************************************************************
|
|
|
|
Name
|
|
====
|
|
|
|
VIDIOC_G_EDID - VIDIOC_S_EDID - VIDIOC_SUBDEV_G_EDID - VIDIOC_SUBDEV_S_EDID - Get or set the EDID of a video receiver/transmitter
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. c:macro:: VIDIOC_G_EDID
|
|
|
|
``int ioctl(int fd, VIDIOC_G_EDID, struct v4l2_edid *argp)``
|
|
|
|
.. c:macro:: VIDIOC_S_EDID
|
|
|
|
``int ioctl(int fd, VIDIOC_S_EDID, struct v4l2_edid *argp)``
|
|
|
|
.. c:macro:: VIDIOC_SUBDEV_G_EDID
|
|
|
|
``int ioctl(int fd, VIDIOC_SUBDEV_G_EDID, struct v4l2_edid *argp)``
|
|
|
|
.. c:macro:: VIDIOC_SUBDEV_S_EDID
|
|
|
|
``int ioctl(int fd, VIDIOC_SUBDEV_S_EDID, struct v4l2_edid *argp)``
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by :c:func:`open()`.
|
|
|
|
``argp``
|
|
Pointer to struct :c:type:`v4l2_edid`.
|
|
|
|
Description
|
|
===========
|
|
|
|
These ioctls can be used to get or set an EDID associated with an input
|
|
from a receiver or an output of a transmitter device. They can be used
|
|
with subdevice nodes (/dev/v4l-subdevX) or with video nodes
|
|
(/dev/videoX).
|
|
|
|
When used with video nodes the ``pad`` field represents the input (for
|
|
video capture devices) or output (for video output devices) index as is
|
|
returned by :ref:`VIDIOC_ENUMINPUT` and
|
|
:ref:`VIDIOC_ENUMOUTPUT` respectively. When used
|
|
with subdevice nodes the ``pad`` field represents the input or output
|
|
pad of the subdevice. If there is no EDID support for the given ``pad``
|
|
value, then the ``EINVAL`` error code will be returned.
|
|
|
|
To get the EDID data the application has to fill in the ``pad``,
|
|
``start_block``, ``blocks`` and ``edid`` fields, zero the ``reserved``
|
|
array and call :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>`. The current EDID from block
|
|
``start_block`` and of size ``blocks`` will be placed in the memory
|
|
``edid`` points to. The ``edid`` pointer must point to memory at least
|
|
``blocks`` * 128 bytes large (the size of one block is 128 bytes).
|
|
|
|
If there are fewer blocks than specified, then the driver will set
|
|
``blocks`` to the actual number of blocks. If there are no EDID blocks
|
|
available at all, then the error code ``ENODATA`` is set.
|
|
|
|
If blocks have to be retrieved from the sink, then this call will block
|
|
until they have been read.
|
|
|
|
If ``start_block`` and ``blocks`` are both set to 0 when
|
|
:ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the
|
|
total number of available EDID blocks and it will return 0 without
|
|
copying any data. This is an easy way to discover how many EDID blocks
|
|
there are.
|
|
|
|
.. note::
|
|
|
|
If there are no EDID blocks available at all, then
|
|
the driver will set ``blocks`` to 0 and it returns 0.
|
|
|
|
To set the EDID blocks of a receiver the application has to fill in the
|
|
``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and
|
|
zero the ``reserved`` array. 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.
|
|
|
|
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 ``blocks`` is set to the
|
|
maximum that the hardware supports. If ``start_block`` is any value
|
|
other than 0 then the error code ``EINVAL`` is set.
|
|
|
|
To disable an EDID you set ``blocks`` 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.
|
|
|
|
.. c:type:: v4l2_edid
|
|
|
|
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
|
|
|
|
.. flat-table:: struct v4l2_edid
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 1 1 2
|
|
|
|
* - __u32
|
|
- ``pad``
|
|
- Pad for which to get/set the EDID blocks. When used with a video
|
|
device node the pad represents the input or output index as
|
|
returned by :ref:`VIDIOC_ENUMINPUT` and
|
|
:ref:`VIDIOC_ENUMOUTPUT` respectively.
|
|
* - __u32
|
|
- ``start_block``
|
|
- Read the EDID from starting with this block. Must be 0 when
|
|
setting the EDID.
|
|
* - __u32
|
|
- ``blocks``
|
|
- 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 ``blocks`` is 0, then the EDID is disabled or
|
|
erased.
|
|
* - __u32
|
|
- ``reserved``\ [5]
|
|
- Reserved for future extensions. Applications and drivers must set
|
|
the array to zero.
|
|
* - __u8 *
|
|
- ``edid``
|
|
- Pointer to memory that contains the EDID. The minimum size is
|
|
``blocks`` * 128.
|
|
|
|
Return Value
|
|
============
|
|
|
|
On success 0 is returned, on error -1 and the ``errno`` variable is set
|
|
appropriately. The generic error codes are described at the
|
|
:ref:`Generic Error Codes <gen-errors>` chapter.
|
|
|
|
``ENODATA``
|
|
The EDID data is not available.
|
|
|
|
``E2BIG``
|
|
The EDID data you provided is more than the hardware can handle.
|