Documentation/userspace-api/media/v4l/vidioc-g-priority.rst

Source file repositories/reference/linux-study-clean/Documentation/userspace-api/media/v4l/vidioc-g-priority.rst

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Linux kernel
Corpus path
Documentation/userspace-api/media/v4l/vidioc-g-priority.rst
Extension
.rst
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2636 bytes
Lines
92
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: V4L

.. _VIDIOC_G_PRIORITY:

******************************************
ioctl VIDIOC_G_PRIORITY, VIDIOC_S_PRIORITY
******************************************

Name
====

VIDIOC_G_PRIORITY - VIDIOC_S_PRIORITY - Query or request the access priority associated with a file descriptor

Synopsis
========

.. c:macro:: VIDIOC_G_PRIORITY

``int ioctl(int fd, VIDIOC_G_PRIORITY, enum v4l2_priority *argp)``

.. c:macro:: VIDIOC_S_PRIORITY

``int ioctl(int fd, VIDIOC_S_PRIORITY, const enum v4l2_priority *argp)``

Arguments
=========

``fd``
    File descriptor returned by :c:func:`open()`.

``argp``
    Pointer to an enum :c:type:`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.

.. c:type:: v4l2_priority

.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|

.. flat-table:: enum v4l2_priority
    :header-rows:  0
    :stub-columns: 0
    :widths:       3 1 4

    * - ``V4L2_PRIORITY_UNSET``
      - 0
      -
    * - ``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.
    * - ``V4L2_PRIORITY_INTERACTIVE``
      - 2
      -
    * - ``V4L2_PRIORITY_DEFAULT``
      - 2
      - Medium priority, usually applications started and interactively
	controlled by the user. For example TV viewers, Teletext browsers,

Annotation

Implementation Notes