mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-28 11:18:45 +07:00
4e03cb760d
As VIDIOC_G_foo is the reference used for VIDIOC_S_foo and VIDIOC_TRY_foo, we need to explicitly name the reference, as otherwise, it will mention the three ioctls altogether, with is not what we want. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
127 lines
3.1 KiB
ReStructuredText
127 lines
3.1 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
|
|
|
|
.. _VIDIOC_G_PRIORITY:
|
|
|
|
******************************************
|
|
ioctl VIDIOC_G_PRIORITY, VIDIOC_S_PRIORITY
|
|
******************************************
|
|
|
|
*man VIDIOC_G_PRIORITY(2)*
|
|
|
|
VIDIOC_S_PRIORITY
|
|
Query or request the access priority associated with a file descriptor
|
|
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. c:function:: int ioctl( int fd, int request, enum v4l2_priority *argp )
|
|
|
|
.. c:function:: int ioctl( int fd, int request, const enum v4l2_priority *argp )
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by :ref:`open() <func-open>`.
|
|
|
|
``request``
|
|
VIDIOC_G_PRIORITY, VIDIOC_S_PRIORITY
|
|
|
|
``argp``
|
|
Pointer to an enum v4l2_priority type.
|
|
|
|
|
|
Description
|
|
===========
|
|
|
|
To query the current access priority applications call the
|
|
:ref:`VIDIOC_G_PRIORITY <VIDIOC_G_PRIORITY>` ioctl with a pointer to an enum v4l2_priority
|
|
variable where the driver stores the current priority.
|
|
|
|
To request an access priority applications store the desired priority in
|
|
an enum v4l2_priority variable and call :ref:`VIDIOC_S_PRIORITY <VIDIOC_G_PRIORITY>` ioctl
|
|
with a pointer to this variable.
|
|
|
|
|
|
.. _v4l2-priority:
|
|
|
|
.. flat-table:: enum v4l2_priority
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 3 1 4
|
|
|
|
|
|
- .. row 1
|
|
|
|
- ``V4L2_PRIORITY_UNSET``
|
|
|
|
- 0
|
|
|
|
-
|
|
|
|
- .. row 2
|
|
|
|
- ``V4L2_PRIORITY_BACKGROUND``
|
|
|
|
- 1
|
|
|
|
- Lowest priority, usually applications running in background, for
|
|
example monitoring VBI transmissions. A proxy application running
|
|
in user space will be necessary if multiple applications want to
|
|
read from a device at this priority.
|
|
|
|
- .. row 3
|
|
|
|
- ``V4L2_PRIORITY_INTERACTIVE``
|
|
|
|
- 2
|
|
|
|
-
|
|
|
|
- .. row 4
|
|
|
|
- ``V4L2_PRIORITY_DEFAULT``
|
|
|
|
- 2
|
|
|
|
- Medium priority, usually applications started and interactively
|
|
controlled by the user. For example TV viewers, Teletext browsers,
|
|
or just "panel" applications to change the channel or video
|
|
controls. This is the default priority unless an application
|
|
requests another.
|
|
|
|
- .. row 5
|
|
|
|
- ``V4L2_PRIORITY_RECORD``
|
|
|
|
- 3
|
|
|
|
- Highest priority. Only one file descriptor can have this priority,
|
|
it blocks any other fd from changing device properties. Usually
|
|
applications which must not be interrupted, like video recording.
|
|
|
|
|
|
|
|
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.
|
|
|
|
EINVAL
|
|
The requested priority value is invalid.
|
|
|
|
EBUSY
|
|
Another application already requested higher priority.
|
|
|
|
|
|
.. ------------------------------------------------------------------------------
|
|
.. This file was automatically converted from DocBook-XML with the dbxml
|
|
.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
|
|
.. from the linux kernel, refer to:
|
|
..
|
|
.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
|
|
.. ------------------------------------------------------------------------------
|