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authorLinus Torvalds <torvalds@linux-foundation.org>2016-07-28 00:58:31 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-28 00:58:31 +0300
commitff9a082fda424257976f08fce942609f358015e0 (patch)
tree478e6b449b19baaf842369a13923499ce83ef895 /Documentation/media/uapi/v4l/vidioc-g-edid.rst
parent6a492b0f23d28e1f946cdf08e54617484400dafb (diff)
parent85538b1ad145c67198cb55d02de14ba269cc323d (diff)
downloadlinux-ff9a082fda424257976f08fce942609f358015e0.tar.xz
Merge tag 'media/v4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media documentation updates from Mauro Carvalho Chehab: "This patch series does the conversion of all media documentation stuff to Restrutured Text markup format and add them to the Documentation/index.rst file. The media documentation was grouped into 4 books: - media uAPI - media kAPI - V4L driver-specific documentation - DVB driver-specific documentation It also contains several documentation improvements and one fixup patch for a core issue with cropcap. PS. After this patch series, the media DocBook is deprecated and should be removed. I'll add such patch on a future pull request" * tag 'media/v4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (322 commits) [media] cx23885-cardlist.rst: add a new card [media] doc-rst: add some needed escape codes [media] doc-rst: kapi: use :c:func: instead of :cpp:func doc-rst: kernel-doc: fix a change introduced by mistake [media] v4l2-ioctl.h add debug info for struct v4l2_ioctl_ops [media] dvb_ringbuffer.h: some documentation improvements [media] v4l2-ctrls.h: fully document the header file [media] doc-rst: Fix some typedef ugly warnings [media] doc-rst: reorganize the kAPI v4l2 chapters [media] rename v4l2-framework.rst to v4l2-intro.rst [media] move V4L2 clocks to a separate .rst file [media] v4l2-fh.rst: add cross references and markups [media] v4l2-fh.rst: add fh contents from v4l2-framework.rst [media] v4l2-fh.h: add documentation for it [media] v4l2-event.rst: add cross-references and markups [media] v4l2-event.h: document all functions [media] v4l2-event.rst: add text from v4l2-framework.rst [media] v4l2-framework.rst: remove videobuf quick chapter [media] v4l2-dev: add cross-references and improve markup [media] doc-rst: move v4l2-dev doc to a separate file ...
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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _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
+========
+
+.. cpp:function:: int ioctl( int fd, int request, struct v4l2_edid *argp )
+
+
+Arguments
+=========
+
+``fd``
+ File descriptor returned by :ref:`open() <func-open>`.
+
+``request``
+ VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID,
+ VIDIOC_SUBDEV_S_EDID
+
+``argp``
+
+
+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.
+
+
+.. _v4l2-edid:
+
+.. flat-table:: struct v4l2_edid
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2
+
+
+ - .. row 1
+
+ - __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.
+
+ - .. row 2
+
+ - __u32
+
+ - ``start_block``
+
+ - Read the EDID from starting with this block. Must be 0 when
+ setting the EDID.
+
+ - .. row 3
+
+ - __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.
+
+ - .. row 4
+
+ - __u32
+
+ - ``reserved``\ [5]
+
+ - Reserved for future extensions. Applications and drivers must set
+ the array to zero.
+
+ - .. row 5
+
+ - __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.