162306a36Sopenharmony_ci.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 262306a36Sopenharmony_ci.. c:namespace:: V4L 362306a36Sopenharmony_ci 462306a36Sopenharmony_ci.. _VIDIOC_G_PRIORITY: 562306a36Sopenharmony_ci 662306a36Sopenharmony_ci****************************************** 762306a36Sopenharmony_ciioctl VIDIOC_G_PRIORITY, VIDIOC_S_PRIORITY 862306a36Sopenharmony_ci****************************************** 962306a36Sopenharmony_ci 1062306a36Sopenharmony_ciName 1162306a36Sopenharmony_ci==== 1262306a36Sopenharmony_ci 1362306a36Sopenharmony_ciVIDIOC_G_PRIORITY - VIDIOC_S_PRIORITY - Query or request the access priority associated with a file descriptor 1462306a36Sopenharmony_ci 1562306a36Sopenharmony_ciSynopsis 1662306a36Sopenharmony_ci======== 1762306a36Sopenharmony_ci 1862306a36Sopenharmony_ci.. c:macro:: VIDIOC_G_PRIORITY 1962306a36Sopenharmony_ci 2062306a36Sopenharmony_ci``int ioctl(int fd, VIDIOC_G_PRIORITY, enum v4l2_priority *argp)`` 2162306a36Sopenharmony_ci 2262306a36Sopenharmony_ci.. c:macro:: VIDIOC_S_PRIORITY 2362306a36Sopenharmony_ci 2462306a36Sopenharmony_ci``int ioctl(int fd, VIDIOC_S_PRIORITY, const enum v4l2_priority *argp)`` 2562306a36Sopenharmony_ci 2662306a36Sopenharmony_ciArguments 2762306a36Sopenharmony_ci========= 2862306a36Sopenharmony_ci 2962306a36Sopenharmony_ci``fd`` 3062306a36Sopenharmony_ci File descriptor returned by :c:func:`open()`. 3162306a36Sopenharmony_ci 3262306a36Sopenharmony_ci``argp`` 3362306a36Sopenharmony_ci Pointer to an enum :c:type:`v4l2_priority` type. 3462306a36Sopenharmony_ci 3562306a36Sopenharmony_ciDescription 3662306a36Sopenharmony_ci=========== 3762306a36Sopenharmony_ci 3862306a36Sopenharmony_ciTo query the current access priority applications call the 3962306a36Sopenharmony_ci:ref:`VIDIOC_G_PRIORITY <VIDIOC_G_PRIORITY>` ioctl with a pointer to an enum v4l2_priority 4062306a36Sopenharmony_civariable where the driver stores the current priority. 4162306a36Sopenharmony_ci 4262306a36Sopenharmony_ciTo request an access priority applications store the desired priority in 4362306a36Sopenharmony_cian enum v4l2_priority variable and call :ref:`VIDIOC_S_PRIORITY <VIDIOC_G_PRIORITY>` ioctl 4462306a36Sopenharmony_ciwith a pointer to this variable. 4562306a36Sopenharmony_ci 4662306a36Sopenharmony_ci.. c:type:: v4l2_priority 4762306a36Sopenharmony_ci 4862306a36Sopenharmony_ci.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}| 4962306a36Sopenharmony_ci 5062306a36Sopenharmony_ci.. flat-table:: enum v4l2_priority 5162306a36Sopenharmony_ci :header-rows: 0 5262306a36Sopenharmony_ci :stub-columns: 0 5362306a36Sopenharmony_ci :widths: 3 1 4 5462306a36Sopenharmony_ci 5562306a36Sopenharmony_ci * - ``V4L2_PRIORITY_UNSET`` 5662306a36Sopenharmony_ci - 0 5762306a36Sopenharmony_ci - 5862306a36Sopenharmony_ci * - ``V4L2_PRIORITY_BACKGROUND`` 5962306a36Sopenharmony_ci - 1 6062306a36Sopenharmony_ci - Lowest priority, usually applications running in background, for 6162306a36Sopenharmony_ci example monitoring VBI transmissions. A proxy application running 6262306a36Sopenharmony_ci in user space will be necessary if multiple applications want to 6362306a36Sopenharmony_ci read from a device at this priority. 6462306a36Sopenharmony_ci * - ``V4L2_PRIORITY_INTERACTIVE`` 6562306a36Sopenharmony_ci - 2 6662306a36Sopenharmony_ci - 6762306a36Sopenharmony_ci * - ``V4L2_PRIORITY_DEFAULT`` 6862306a36Sopenharmony_ci - 2 6962306a36Sopenharmony_ci - Medium priority, usually applications started and interactively 7062306a36Sopenharmony_ci controlled by the user. For example TV viewers, Teletext browsers, 7162306a36Sopenharmony_ci or just "panel" applications to change the channel or video 7262306a36Sopenharmony_ci controls. This is the default priority unless an application 7362306a36Sopenharmony_ci requests another. 7462306a36Sopenharmony_ci * - ``V4L2_PRIORITY_RECORD`` 7562306a36Sopenharmony_ci - 3 7662306a36Sopenharmony_ci - Highest priority. Only one file descriptor can have this priority, 7762306a36Sopenharmony_ci it blocks any other fd from changing device properties. Usually 7862306a36Sopenharmony_ci applications which must not be interrupted, like video recording. 7962306a36Sopenharmony_ci 8062306a36Sopenharmony_ciReturn Value 8162306a36Sopenharmony_ci============ 8262306a36Sopenharmony_ci 8362306a36Sopenharmony_ciOn success 0 is returned, on error -1 and the ``errno`` variable is set 8462306a36Sopenharmony_ciappropriately. The generic error codes are described at the 8562306a36Sopenharmony_ci:ref:`Generic Error Codes <gen-errors>` chapter. 8662306a36Sopenharmony_ci 8762306a36Sopenharmony_ciEINVAL 8862306a36Sopenharmony_ci The requested priority value is invalid. 8962306a36Sopenharmony_ci 9062306a36Sopenharmony_ciEBUSY 9162306a36Sopenharmony_ci Another application already requested higher priority. 92