18c2ecf20Sopenharmony_ci.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 28c2ecf20Sopenharmony_ci.. c:namespace:: V4L 38c2ecf20Sopenharmony_ci 48c2ecf20Sopenharmony_ci.. _VIDIOC_G_CTRL: 58c2ecf20Sopenharmony_ci 68c2ecf20Sopenharmony_ci********************************** 78c2ecf20Sopenharmony_ciioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL 88c2ecf20Sopenharmony_ci********************************** 98c2ecf20Sopenharmony_ci 108c2ecf20Sopenharmony_ciName 118c2ecf20Sopenharmony_ci==== 128c2ecf20Sopenharmony_ci 138c2ecf20Sopenharmony_ciVIDIOC_G_CTRL - VIDIOC_S_CTRL - Get or set the value of a control 148c2ecf20Sopenharmony_ci 158c2ecf20Sopenharmony_ciSynopsis 168c2ecf20Sopenharmony_ci======== 178c2ecf20Sopenharmony_ci 188c2ecf20Sopenharmony_ci.. c:macro:: VIDIOC_G_CTRL 198c2ecf20Sopenharmony_ci 208c2ecf20Sopenharmony_ci``int ioctl(int fd, VIDIOC_G_CTRL, struct v4l2_control *argp)`` 218c2ecf20Sopenharmony_ci 228c2ecf20Sopenharmony_ci.. c:macro:: VIDIOC_S_CTRL 238c2ecf20Sopenharmony_ci 248c2ecf20Sopenharmony_ci``int ioctl(int fd, VIDIOC_S_CTRL, struct v4l2_control *argp)`` 258c2ecf20Sopenharmony_ci 268c2ecf20Sopenharmony_ciArguments 278c2ecf20Sopenharmony_ci========= 288c2ecf20Sopenharmony_ci 298c2ecf20Sopenharmony_ci``fd`` 308c2ecf20Sopenharmony_ci File descriptor returned by :c:func:`open()`. 318c2ecf20Sopenharmony_ci 328c2ecf20Sopenharmony_ci``argp`` 338c2ecf20Sopenharmony_ci Pointer to struct :c:type:`v4l2_control`. 348c2ecf20Sopenharmony_ci 358c2ecf20Sopenharmony_ciDescription 368c2ecf20Sopenharmony_ci=========== 378c2ecf20Sopenharmony_ci 388c2ecf20Sopenharmony_ciTo get the current value of a control applications initialize the ``id`` 398c2ecf20Sopenharmony_cifield of a struct :c:type:`v4l2_control` and call the 408c2ecf20Sopenharmony_ci:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` ioctl with a pointer to this structure. To change the 418c2ecf20Sopenharmony_civalue of a control applications initialize the ``id`` and ``value`` 428c2ecf20Sopenharmony_cifields of a struct :c:type:`v4l2_control` and call the 438c2ecf20Sopenharmony_ci:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctl. 448c2ecf20Sopenharmony_ci 458c2ecf20Sopenharmony_ciWhen the ``id`` is invalid drivers return an ``EINVAL`` error code. When the 468c2ecf20Sopenharmony_ci``value`` is out of bounds drivers can choose to take the closest valid 478c2ecf20Sopenharmony_civalue or return an ``ERANGE`` error code, whatever seems more appropriate. 488c2ecf20Sopenharmony_ciHowever, :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` is a write-only ioctl, it does not return the 498c2ecf20Sopenharmony_ciactual new value. If the ``value`` is inappropriate for the control 508c2ecf20Sopenharmony_ci(e.g. if it refers to an unsupported menu index of a menu control), then 518c2ecf20Sopenharmony_ciEINVAL error code is returned as well. 528c2ecf20Sopenharmony_ci 538c2ecf20Sopenharmony_ciThese ioctls work only with user controls. For other control classes the 548c2ecf20Sopenharmony_ci:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`, 558c2ecf20Sopenharmony_ci:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` or 568c2ecf20Sopenharmony_ci:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` must be used. 578c2ecf20Sopenharmony_ci 588c2ecf20Sopenharmony_ci.. c:type:: v4l2_control 598c2ecf20Sopenharmony_ci 608c2ecf20Sopenharmony_ci.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| 618c2ecf20Sopenharmony_ci 628c2ecf20Sopenharmony_ci.. flat-table:: struct v4l2_control 638c2ecf20Sopenharmony_ci :header-rows: 0 648c2ecf20Sopenharmony_ci :stub-columns: 0 658c2ecf20Sopenharmony_ci :widths: 1 1 2 668c2ecf20Sopenharmony_ci 678c2ecf20Sopenharmony_ci * - __u32 688c2ecf20Sopenharmony_ci - ``id`` 698c2ecf20Sopenharmony_ci - Identifies the control, set by the application. 708c2ecf20Sopenharmony_ci * - __s32 718c2ecf20Sopenharmony_ci - ``value`` 728c2ecf20Sopenharmony_ci - New value or current value. 738c2ecf20Sopenharmony_ci 748c2ecf20Sopenharmony_ciReturn Value 758c2ecf20Sopenharmony_ci============ 768c2ecf20Sopenharmony_ci 778c2ecf20Sopenharmony_ciOn success 0 is returned, on error -1 and the ``errno`` variable is set 788c2ecf20Sopenharmony_ciappropriately. The generic error codes are described at the 798c2ecf20Sopenharmony_ci:ref:`Generic Error Codes <gen-errors>` chapter. 808c2ecf20Sopenharmony_ci 818c2ecf20Sopenharmony_ciEINVAL 828c2ecf20Sopenharmony_ci The struct :c:type:`v4l2_control` ``id`` is invalid 838c2ecf20Sopenharmony_ci or the ``value`` is inappropriate for the given control (i.e. if a 848c2ecf20Sopenharmony_ci menu item is selected that is not supported by the driver according 858c2ecf20Sopenharmony_ci to :ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>`). 868c2ecf20Sopenharmony_ci 878c2ecf20Sopenharmony_ciERANGE 888c2ecf20Sopenharmony_ci The struct :c:type:`v4l2_control` ``value`` is out of 898c2ecf20Sopenharmony_ci bounds. 908c2ecf20Sopenharmony_ci 918c2ecf20Sopenharmony_ciEBUSY 928c2ecf20Sopenharmony_ci The control is temporarily not changeable, possibly because another 938c2ecf20Sopenharmony_ci applications took over control of the device function this control 948c2ecf20Sopenharmony_ci belongs to. 958c2ecf20Sopenharmony_ci 968c2ecf20Sopenharmony_ciEACCES 978c2ecf20Sopenharmony_ci Attempt to set a read-only control or to get a write-only control. 98