56ab8cdbc1
There is no way to control the standard of subdevices which are part of a media device. The ioctls which exists all target video devices explicitly and the idea is that the video device should talk to the subdevice. For subdevices part of a media graph this is not possible and the standard must be controlled on the subdev device directly. Add four new ioctls to be able to directly interact with subdevices and control the video standard; VIDIOC_SUBDEV_ENUMSTD, VIDIOC_SUBDEV_G_STD, VIDIOC_SUBDEV_S_STD and VIDIOC_SUBDEV_QUERYSTD. Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
75 lines
2.4 KiB
ReStructuredText
75 lines
2.4 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
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.. _VIDIOC_G_STD:
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**************************************************************************
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ioctl VIDIOC_G_STD, VIDIOC_S_STD, VIDIOC_SUBDEV_G_STD, VIDIOC_SUBDEV_S_STD
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**************************************************************************
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Name
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====
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VIDIOC_G_STD - VIDIOC_S_STD - VIDIOC_SUBDEV_G_STD - VIDIOC_SUBDEV_S_STD - Query or select the video standard of the current input
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Synopsis
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========
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.. c:function:: int ioctl( int fd, VIDIOC_G_STD, v4l2_std_id *argp )
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:name: VIDIOC_G_STD
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.. c:function:: int ioctl( int fd, VIDIOC_S_STD, const v4l2_std_id *argp )
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:name: VIDIOC_S_STD
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.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_STD, v4l2_std_id *argp )
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:name: VIDIOC_SUBDEV_G_STD
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.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_STD, const v4l2_std_id *argp )
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:name: VIDIOC_SUBDEV_S_STD
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Arguments
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=========
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``fd``
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File descriptor returned by :ref:`open() <func-open>`.
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``argp``
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Pointer to :c:type:`v4l2_std_id`.
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Description
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===========
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To query and select the current video standard applications use the
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:ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a
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:ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD <VIDIOC_G_STD>`
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can return a single flag or a set of flags as in struct
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:c:type:`v4l2_standard` field ``id``. The flags must be
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unambiguous such that they appear in only one enumerated
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struct :c:type:`v4l2_standard` structure.
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:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` accepts one or more flags, being a write-only ioctl it
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does not return the actual new standard as :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` does. When
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no flags are given or the current input does not support the requested
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standard the driver returns an ``EINVAL`` error code. When the standard set
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is ambiguous drivers may return ``EINVAL`` or choose any of the requested
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standards. If the current input or output does not support standard
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video timings (e.g. if :ref:`VIDIOC_ENUMINPUT`
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does not set the ``V4L2_IN_CAP_STD`` flag), then ``ENODATA`` error code is
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returned.
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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EINVAL
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The :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` parameter was unsuitable.
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ENODATA
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Standard video timings are not supported for this input or output.
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