162306a36Sopenharmony_ci.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 262306a36Sopenharmony_ci.. c:namespace:: V4L 362306a36Sopenharmony_ci 462306a36Sopenharmony_ci.. _VIDIOC_G_CTRL: 562306a36Sopenharmony_ci 662306a36Sopenharmony_ci********************************** 762306a36Sopenharmony_ciioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL 862306a36Sopenharmony_ci********************************** 962306a36Sopenharmony_ci 1062306a36Sopenharmony_ciName 1162306a36Sopenharmony_ci==== 1262306a36Sopenharmony_ci 1362306a36Sopenharmony_ciVIDIOC_G_CTRL - VIDIOC_S_CTRL - Get or set the value of a control 1462306a36Sopenharmony_ci 1562306a36Sopenharmony_ciSynopsis 1662306a36Sopenharmony_ci======== 1762306a36Sopenharmony_ci 1862306a36Sopenharmony_ci.. c:macro:: VIDIOC_G_CTRL 1962306a36Sopenharmony_ci 2062306a36Sopenharmony_ci``int ioctl(int fd, VIDIOC_G_CTRL, struct v4l2_control *argp)`` 2162306a36Sopenharmony_ci 2262306a36Sopenharmony_ci.. c:macro:: VIDIOC_S_CTRL 2362306a36Sopenharmony_ci 2462306a36Sopenharmony_ci``int ioctl(int fd, VIDIOC_S_CTRL, struct v4l2_control *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 struct :c:type:`v4l2_control`. 3462306a36Sopenharmony_ci 3562306a36Sopenharmony_ciDescription 3662306a36Sopenharmony_ci=========== 3762306a36Sopenharmony_ci 3862306a36Sopenharmony_ciTo get the current value of a control applications initialize the ``id`` 3962306a36Sopenharmony_cifield of a struct :c:type:`v4l2_control` and call the 4062306a36Sopenharmony_ci:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` ioctl with a pointer to this structure. To change the 4162306a36Sopenharmony_civalue of a control applications initialize the ``id`` and ``value`` 4262306a36Sopenharmony_cifields of a struct :c:type:`v4l2_control` and call the 4362306a36Sopenharmony_ci:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctl. 4462306a36Sopenharmony_ci 4562306a36Sopenharmony_ciWhen the ``id`` is invalid drivers return an ``EINVAL`` error code. When the 4662306a36Sopenharmony_ci``value`` is out of bounds drivers can choose to take the closest valid 4762306a36Sopenharmony_civalue or return an ``ERANGE`` error code, whatever seems more appropriate. 4862306a36Sopenharmony_ciHowever, :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` is a write-only ioctl, it does not return the 4962306a36Sopenharmony_ciactual new value. If the ``value`` is inappropriate for the control 5062306a36Sopenharmony_ci(e.g. if it refers to an unsupported menu index of a menu control), then 5162306a36Sopenharmony_ciEINVAL error code is returned as well. 5262306a36Sopenharmony_ci 5362306a36Sopenharmony_ciThese ioctls work only with user controls. For other control classes the 5462306a36Sopenharmony_ci:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`, 5562306a36Sopenharmony_ci:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` or 5662306a36Sopenharmony_ci:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` must be used. 5762306a36Sopenharmony_ci 5862306a36Sopenharmony_ci.. c:type:: v4l2_control 5962306a36Sopenharmony_ci 6062306a36Sopenharmony_ci.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| 6162306a36Sopenharmony_ci 6262306a36Sopenharmony_ci.. flat-table:: struct v4l2_control 6362306a36Sopenharmony_ci :header-rows: 0 6462306a36Sopenharmony_ci :stub-columns: 0 6562306a36Sopenharmony_ci :widths: 1 1 2 6662306a36Sopenharmony_ci 6762306a36Sopenharmony_ci * - __u32 6862306a36Sopenharmony_ci - ``id`` 6962306a36Sopenharmony_ci - Identifies the control, set by the application. 7062306a36Sopenharmony_ci * - __s32 7162306a36Sopenharmony_ci - ``value`` 7262306a36Sopenharmony_ci - New value or current value. 7362306a36Sopenharmony_ci 7462306a36Sopenharmony_ciReturn Value 7562306a36Sopenharmony_ci============ 7662306a36Sopenharmony_ci 7762306a36Sopenharmony_ciOn success 0 is returned, on error -1 and the ``errno`` variable is set 7862306a36Sopenharmony_ciappropriately. The generic error codes are described at the 7962306a36Sopenharmony_ci:ref:`Generic Error Codes <gen-errors>` chapter. 8062306a36Sopenharmony_ci 8162306a36Sopenharmony_ciEINVAL 8262306a36Sopenharmony_ci The struct :c:type:`v4l2_control` ``id`` is invalid 8362306a36Sopenharmony_ci or the ``value`` is inappropriate for the given control (i.e. if a 8462306a36Sopenharmony_ci menu item is selected that is not supported by the driver according 8562306a36Sopenharmony_ci to :ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>`). 8662306a36Sopenharmony_ci 8762306a36Sopenharmony_ciERANGE 8862306a36Sopenharmony_ci The struct :c:type:`v4l2_control` ``value`` is out of 8962306a36Sopenharmony_ci bounds. 9062306a36Sopenharmony_ci 9162306a36Sopenharmony_ciEBUSY 9262306a36Sopenharmony_ci The control is temporarily not changeable, possibly because another 9362306a36Sopenharmony_ci applications took over control of the device function this control 9462306a36Sopenharmony_ci belongs to. 9562306a36Sopenharmony_ci 9662306a36Sopenharmony_ciEACCES 9762306a36Sopenharmony_ci Attempt to set a read-only control or to get a write-only control. 9862306a36Sopenharmony_ci 9962306a36Sopenharmony_ci Or if there is an attempt to set an inactive control and the driver is 10062306a36Sopenharmony_ci not capable of caching the new value until the control is active again. 101