64e4954619
The conversion script added some comments at the end. They point to the original DocBook files, with will be removed after the manual fixes. So, they'll be pointing to nowere. So, remove those comments. They'll be forever stored at the Kernel tree. So, if someone wants the references, it is just a matter of looking at the backlog. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
118 lines
2.7 KiB
ReStructuredText
118 lines
2.7 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
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.. _VIDIOC_G_PRIORITY:
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******************************************
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ioctl VIDIOC_G_PRIORITY, VIDIOC_S_PRIORITY
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******************************************
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*man VIDIOC_G_PRIORITY(2)*
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VIDIOC_S_PRIORITY
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Query or request the access priority associated with a file descriptor
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Synopsis
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========
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.. c:function:: int ioctl( int fd, int request, enum v4l2_priority *argp )
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.. c:function:: int ioctl( int fd, int request, const enum v4l2_priority *argp )
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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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``request``
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VIDIOC_G_PRIORITY, VIDIOC_S_PRIORITY
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``argp``
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Pointer to an enum v4l2_priority type.
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Description
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===========
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To query the current access priority applications call the
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:ref:`VIDIOC_G_PRIORITY <VIDIOC_G_PRIORITY>` ioctl with a pointer to an enum v4l2_priority
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variable where the driver stores the current priority.
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To request an access priority applications store the desired priority in
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an enum v4l2_priority variable and call :ref:`VIDIOC_S_PRIORITY <VIDIOC_G_PRIORITY>` ioctl
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with a pointer to this variable.
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.. _v4l2-priority:
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.. flat-table:: enum v4l2_priority
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:header-rows: 0
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:stub-columns: 0
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:widths: 3 1 4
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- .. row 1
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- ``V4L2_PRIORITY_UNSET``
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- 0
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-
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- .. row 2
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- ``V4L2_PRIORITY_BACKGROUND``
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- 1
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- Lowest priority, usually applications running in background, for
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example monitoring VBI transmissions. A proxy application running
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in user space will be necessary if multiple applications want to
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read from a device at this priority.
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- .. row 3
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- ``V4L2_PRIORITY_INTERACTIVE``
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- 2
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-
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- .. row 4
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- ``V4L2_PRIORITY_DEFAULT``
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- 2
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- Medium priority, usually applications started and interactively
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controlled by the user. For example TV viewers, Teletext browsers,
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or just "panel" applications to change the channel or video
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controls. This is the default priority unless an application
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requests another.
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- .. row 5
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- ``V4L2_PRIORITY_RECORD``
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- 3
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- Highest priority. Only one file descriptor can have this priority,
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it blocks any other fd from changing device properties. Usually
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applications which must not be interrupted, like video recording.
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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 requested priority value is invalid.
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EBUSY
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Another application already requested higher priority.
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