1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_G_EXT_CTRLS: 5 6****************************************************************** 7ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS 8****************************************************************** 9 10Name 11==== 12 13VIDIOC_G_EXT_CTRLS - VIDIOC_S_EXT_CTRLS - VIDIOC_TRY_EXT_CTRLS - Get or set the value of several controls, try control values 14 15Synopsis 16======== 17 18.. c:macro:: VIDIOC_G_EXT_CTRLS 19 20``int ioctl(int fd, VIDIOC_G_EXT_CTRLS, struct v4l2_ext_controls *argp)`` 21 22.. c:macro:: VIDIOC_S_EXT_CTRLS 23 24``int ioctl(int fd, VIDIOC_S_EXT_CTRLS, struct v4l2_ext_controls *argp)`` 25 26.. c:macro:: VIDIOC_TRY_EXT_CTRLS 27 28``int ioctl(int fd, VIDIOC_TRY_EXT_CTRLS, struct v4l2_ext_controls *argp)`` 29 30Arguments 31========= 32 33``fd`` 34 File descriptor returned by :c:func:`open()`. 35 36``argp`` 37 Pointer to struct :c:type:`v4l2_ext_controls`. 38 39Description 40=========== 41 42These ioctls allow the caller to get or set multiple controls 43atomically. Control IDs are grouped into control classes (see 44:ref:`ctrl-class`) and all controls in the control array must belong 45to the same control class. 46 47Applications must always fill in the ``count``, ``which``, ``controls`` 48and ``reserved`` fields of struct 49:c:type:`v4l2_ext_controls`, and initialize the 50struct :c:type:`v4l2_ext_control` array pointed to 51by the ``controls`` fields. 52 53To get the current value of a set of controls applications initialize 54the ``id``, ``size`` and ``reserved2`` fields of each struct 55:c:type:`v4l2_ext_control` and call the 56:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctl. String controls must also set the 57``string`` field. Controls of compound types 58(``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is set) must set the ``ptr`` field. 59 60If the ``size`` is too small to receive the control result (only 61relevant for pointer-type controls like strings), then the driver will 62set ``size`` to a valid value and return an ``ENOSPC`` error code. You 63should re-allocate the memory to this new size and try again. For the 64string type it is possible that the same issue occurs again if the 65string has grown in the meantime. It is recommended to call 66:ref:`VIDIOC_QUERYCTRL` first and use 67``maximum``\ +1 as the new ``size`` value. It is guaranteed that that is 68sufficient memory. 69 70N-dimensional arrays are set and retrieved row-by-row. You cannot set a 71partial array, all elements have to be set or retrieved. The total size 72is calculated as ``elems`` * ``elem_size``. These values can be obtained 73by calling :ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>`. 74 75To change the value of a set of controls applications initialize the 76``id``, ``size``, ``reserved2`` and ``value/value64/string/ptr`` fields 77of each struct :c:type:`v4l2_ext_control` and call 78the :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctl. The controls will only be set if *all* 79control values are valid. 80 81To check if a set of controls have correct values applications 82initialize the ``id``, ``size``, ``reserved2`` and 83``value/value64/string/ptr`` fields of each struct 84:c:type:`v4l2_ext_control` and call the 85:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctl. It is up to the driver whether wrong 86values are automatically adjusted to a valid value or if an error is 87returned. 88 89When the ``id`` or ``which`` is invalid drivers return an ``EINVAL`` error 90code. When the value is out of bounds drivers can choose to take the 91closest valid value or return an ``ERANGE`` error code, whatever seems more 92appropriate. In the first case the new value is set in struct 93:c:type:`v4l2_ext_control`. If the new control value 94is inappropriate (e.g. the given menu index is not supported by the menu 95control), then this will also result in an ``EINVAL`` error code error. 96 97If ``request_fd`` is set to a not-yet-queued :ref:`request <media-request-api>` 98file descriptor and ``which`` is set to ``V4L2_CTRL_WHICH_REQUEST_VAL``, 99then the controls are not applied immediately when calling 100:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`, but instead are applied by 101the driver for the buffer associated with the same request. 102If the device does not support requests, then ``EACCES`` will be returned. 103If requests are supported but an invalid request file descriptor is given, 104then ``EINVAL`` will be returned. 105 106An attempt to call :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` for a 107request that has already been queued will result in an ``EBUSY`` error. 108 109If ``request_fd`` is specified and ``which`` is set to 110``V4L2_CTRL_WHICH_REQUEST_VAL`` during a call to 111:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`, then it will return the 112values of the controls at the time of request completion. 113If the request is not yet completed, then this will result in an 114``EACCES`` error. 115 116The driver will only set/get these controls if all control values are 117correct. This prevents the situation where only some of the controls 118were set/get. Only low-level errors (e. g. a failed i2c command) can 119still cause this situation. 120 121.. tabularcolumns:: |p{6.8cm}|p{4.0cm}|p{6.5cm}| 122 123.. c:type:: v4l2_ext_control 124 125.. raw:: latex 126 127 \footnotesize 128 129.. cssclass:: longtable 130 131.. flat-table:: struct v4l2_ext_control 132 :header-rows: 0 133 :stub-columns: 0 134 :widths: 1 1 2 135 136 * - __u32 137 - ``id`` 138 - Identifies the control, set by the application. 139 * - __u32 140 - ``size`` 141 - The total size in bytes of the payload of this control. 142 * - :cspan:`2` The ``size`` field is normally 0, but for pointer 143 controls this should be set to the size of the memory that contains 144 the payload or that will receive the payload. 145 If :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` finds that this value 146 is less than is required to store the payload result, then it is set 147 to a value large enough to store the payload result and ``ENOSPC`` is 148 returned. 149 150 .. note:: 151 152 For string controls, this ``size`` field should 153 not be confused with the length of the string. This field refers 154 to the size of the memory that contains the string. The actual 155 *length* of the string may well be much smaller. 156 * - __u32 157 - ``reserved2``\ [1] 158 - Reserved for future extensions. Drivers and applications must set 159 the array to zero. 160 * - union { 161 - (anonymous) 162 * - __s32 163 - ``value`` 164 - New value or current value. Valid if this control is not of type 165 ``V4L2_CTRL_TYPE_INTEGER64`` and ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is 166 not set. 167 * - __s64 168 - ``value64`` 169 - New value or current value. Valid if this control is of type 170 ``V4L2_CTRL_TYPE_INTEGER64`` and ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is 171 not set. 172 * - char * 173 - ``string`` 174 - A pointer to a string. Valid if this control is of type 175 ``V4L2_CTRL_TYPE_STRING``. 176 * - __u8 * 177 - ``p_u8`` 178 - A pointer to a matrix control of unsigned 8-bit values. Valid if 179 this control is of type ``V4L2_CTRL_TYPE_U8``. 180 * - __u16 * 181 - ``p_u16`` 182 - A pointer to a matrix control of unsigned 16-bit values. Valid if 183 this control is of type ``V4L2_CTRL_TYPE_U16``. 184 * - __u32 * 185 - ``p_u32`` 186 - A pointer to a matrix control of unsigned 32-bit values. Valid if 187 this control is of type ``V4L2_CTRL_TYPE_U32``. 188 * - __u32 * 189 - ``p_s32`` 190 - A pointer to a matrix control of signed 32-bit values. Valid if 191 this control is of type ``V4L2_CTRL_TYPE_INTEGER`` and 192 ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is set. 193 * - __u32 * 194 - ``p_s64`` 195 - A pointer to a matrix control of signed 64-bit values. Valid if 196 this control is of type ``V4L2_CTRL_TYPE_INTEGER64`` and 197 ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is set. 198 * - struct :c:type:`v4l2_area` * 199 - ``p_area`` 200 - A pointer to a struct :c:type:`v4l2_area`. Valid if this control is 201 of type ``V4L2_CTRL_TYPE_AREA``. 202 * - struct :c:type:`v4l2_ctrl_h264_sps` * 203 - ``p_h264_sps`` 204 - A pointer to a struct :c:type:`v4l2_ctrl_h264_sps`. Valid if this control is 205 of type ``V4L2_CTRL_TYPE_H264_SPS``. 206 * - struct :c:type:`v4l2_ctrl_h264_pps` * 207 - ``p_h264_pps`` 208 - A pointer to a struct :c:type:`v4l2_ctrl_h264_pps`. Valid if this control is 209 of type ``V4L2_CTRL_TYPE_H264_PPS``. 210 * - struct :c:type:`v4l2_ctrl_h264_scaling_matrix` * 211 - ``p_h264_scaling_matrix`` 212 - A pointer to a struct :c:type:`v4l2_ctrl_h264_scaling_matrix`. Valid if this control is 213 of type ``V4L2_CTRL_TYPE_H264_SCALING_MATRIX``. 214 * - struct :c:type:`v4l2_ctrl_h264_pred_weights` * 215 - ``p_h264_pred_weights`` 216 - A pointer to a struct :c:type:`v4l2_ctrl_h264_pred_weights`. Valid if this control is 217 of type ``V4L2_CTRL_TYPE_H264_PRED_WEIGHTS``. 218 * - struct :c:type:`v4l2_ctrl_h264_slice_params` * 219 - ``p_h264_slice_params`` 220 - A pointer to a struct :c:type:`v4l2_ctrl_h264_slice_params`. Valid if this control is 221 of type ``V4L2_CTRL_TYPE_H264_SLICE_PARAMS``. 222 * - struct :c:type:`v4l2_ctrl_h264_decode_params` * 223 - ``p_h264_decode_params`` 224 - A pointer to a struct :c:type:`v4l2_ctrl_h264_decode_params`. Valid if this control is 225 of type ``V4L2_CTRL_TYPE_H264_DECODE_PARAMS``. 226 * - struct :c:type:`v4l2_ctrl_fwht_params` * 227 - ``p_fwht_params`` 228 - A pointer to a struct :c:type:`v4l2_ctrl_fwht_params`. Valid if this control is 229 of type ``V4L2_CTRL_TYPE_FWHT_PARAMS``. 230 * - struct :c:type:`v4l2_ctrl_vp8_frame` * 231 - ``p_vp8_frame`` 232 - A pointer to a struct :c:type:`v4l2_ctrl_vp8_frame`. Valid if this control is 233 of type ``V4L2_CTRL_TYPE_VP8_FRAME``. 234 * - struct :c:type:`v4l2_ctrl_mpeg2_sequence` * 235 - ``p_mpeg2_sequence`` 236 - A pointer to a struct :c:type:`v4l2_ctrl_mpeg2_sequence`. Valid if this control is 237 of type ``V4L2_CTRL_TYPE_MPEG2_SEQUENCE``. 238 * - struct :c:type:`v4l2_ctrl_mpeg2_picture` * 239 - ``p_mpeg2_picture`` 240 - A pointer to a struct :c:type:`v4l2_ctrl_mpeg2_picture`. Valid if this control is 241 of type ``V4L2_CTRL_TYPE_MPEG2_PICTURE``. 242 * - struct :c:type:`v4l2_ctrl_mpeg2_quantisation` * 243 - ``p_mpeg2_quantisation`` 244 - A pointer to a struct :c:type:`v4l2_ctrl_mpeg2_quantisation`. Valid if this control is 245 of type ``V4L2_CTRL_TYPE_MPEG2_QUANTISATION``. 246 * - struct :c:type:`v4l2_ctrl_vp9_compressed_hdr` * 247 - ``p_vp9_compressed_hdr_probs`` 248 - A pointer to a struct :c:type:`v4l2_ctrl_vp9_compressed_hdr`. Valid if this 249 control is of type ``V4L2_CTRL_TYPE_VP9_COMPRESSED_HDR``. 250 * - struct :c:type:`v4l2_ctrl_vp9_frame` * 251 - ``p_vp9_frame`` 252 - A pointer to a struct :c:type:`v4l2_ctrl_vp9_frame`. Valid if this 253 control is of type ``V4L2_CTRL_TYPE_VP9_FRAME``. 254 * - struct :c:type:`v4l2_ctrl_hdr10_cll_info` * 255 - ``p_hdr10_cll`` 256 - A pointer to a struct :c:type:`v4l2_ctrl_hdr10_cll_info`. Valid if this control is 257 of type ``V4L2_CTRL_TYPE_HDR10_CLL_INFO``. 258 * - struct :c:type:`v4l2_ctrl_hdr10_mastering_display` * 259 - ``p_hdr10_mastering`` 260 - A pointer to a struct :c:type:`v4l2_ctrl_hdr10_mastering_display`. Valid if this control is 261 of type ``V4L2_CTRL_TYPE_HDR10_MASTERING_DISPLAY``. 262 * - struct :c:type:`v4l2_ctrl_hevc_sps` * 263 - ``p_hevc_sps`` 264 - A pointer to a struct :c:type:`v4l2_ctrl_hevc_sps`. Valid if this 265 control is of type ``V4L2_CTRL_TYPE_HEVC_SPS``. 266 * - struct :c:type:`v4l2_ctrl_hevc_pps` * 267 - ``p_hevc_pps`` 268 - A pointer to a struct :c:type:`v4l2_ctrl_hevc_pps`. Valid if this 269 control is of type ``V4L2_CTRL_TYPE_HEVC_PPS``. 270 * - struct :c:type:`v4l2_ctrl_hevc_slice_params` * 271 - ``p_hevc_slice_params`` 272 - A pointer to a struct :c:type:`v4l2_ctrl_hevc_slice_params`. Valid if this 273 control is of type ``V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS``. 274 * - struct :c:type:`v4l2_ctrl_hevc_scaling_matrix` * 275 - ``p_hevc_scaling_matrix`` 276 - A pointer to a struct :c:type:`v4l2_ctrl_hevc_scaling_matrix`. Valid if this 277 control is of type ``V4L2_CTRL_TYPE_HEVC_SCALING_MATRIX``. 278 * - struct :c:type:`v4l2_ctrl_hevc_decode_params` * 279 - ``p_hevc_decode_params`` 280 - A pointer to a struct :c:type:`v4l2_ctrl_hevc_decode_params`. Valid if this 281 control is of type ``V4L2_CTRL_TYPE_HEVC_DECODE_PARAMS``. 282 * - void * 283 - ``ptr`` 284 - A pointer to a compound type which can be an N-dimensional array 285 and/or a compound type (the control's type is >= 286 ``V4L2_CTRL_COMPOUND_TYPES``). Valid if 287 ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is set for this control. 288 * - } 289 - 290 291.. raw:: latex 292 293 \normalsize 294 295.. tabularcolumns:: |p{4.0cm}|p{2.5cm}|p{10.8cm}| 296 297.. c:type:: v4l2_ext_controls 298 299.. cssclass:: longtable 300 301.. flat-table:: struct v4l2_ext_controls 302 :header-rows: 0 303 :stub-columns: 0 304 :widths: 1 1 2 305 306 * - union { 307 - (anonymous) 308 * - __u32 309 - ``which`` 310 - Which value of the control to get/set/try. 311 * - :cspan:`2` ``V4L2_CTRL_WHICH_CUR_VAL`` will return the current value of 312 the control, ``V4L2_CTRL_WHICH_DEF_VAL`` will return the default 313 value of the control and ``V4L2_CTRL_WHICH_REQUEST_VAL`` indicates that 314 these controls have to be retrieved from a request or tried/set for 315 a request. In the latter case the ``request_fd`` field contains the 316 file descriptor of the request that should be used. If the device 317 does not support requests, then ``EACCES`` will be returned. 318 319 When using ``V4L2_CTRL_WHICH_DEF_VAL`` be aware that you can only 320 get the default value of the control, you cannot set or try it. 321 322 For backwards compatibility you can also use a control class here 323 (see :ref:`ctrl-class`). In that case all controls have to 324 belong to that control class. This usage is deprecated, instead 325 just use ``V4L2_CTRL_WHICH_CUR_VAL``. There are some very old 326 drivers that do not yet support ``V4L2_CTRL_WHICH_CUR_VAL`` and 327 that require a control class here. You can test for such drivers 328 by setting ``which`` to ``V4L2_CTRL_WHICH_CUR_VAL`` and calling 329 :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` with a count of 0. 330 If that fails, then the driver does not support ``V4L2_CTRL_WHICH_CUR_VAL``. 331 * - __u32 332 - ``ctrl_class`` 333 - Deprecated name kept for backwards compatibility. Use ``which`` instead. 334 * - } 335 - 336 * - __u32 337 - ``count`` 338 - The number of controls in the controls array. May also be zero. 339 * - __u32 340 - ``error_idx`` 341 - Index of the failing control. Set by the driver in case of an error. 342 * - :cspan:`2` If the error is associated 343 with a particular control, then ``error_idx`` is set to the index 344 of that control. If the error is not related to a specific 345 control, or the validation step failed (see below), then 346 ``error_idx`` is set to ``count``. The value is undefined if the 347 ioctl returned 0 (success). 348 349 Before controls are read from/written to hardware a validation 350 step takes place: this checks if all controls in the list are 351 valid controls, if no attempt is made to write to a read-only 352 control or read from a write-only control, and any other up-front 353 checks that can be done without accessing the hardware. The exact 354 validations done during this step are driver dependent since some 355 checks might require hardware access for some devices, thus making 356 it impossible to do those checks up-front. However, drivers should 357 make a best-effort to do as many up-front checks as possible. 358 359 This check is done to avoid leaving the hardware in an 360 inconsistent state due to easy-to-avoid problems. But it leads to 361 another problem: the application needs to know whether an error 362 came from the validation step (meaning that the hardware was not 363 touched) or from an error during the actual reading from/writing 364 to hardware. 365 366 The, in hindsight quite poor, solution for that is to set 367 ``error_idx`` to ``count`` if the validation failed. This has the 368 unfortunate side-effect that it is not possible to see which 369 control failed the validation. If the validation was successful 370 and the error happened while accessing the hardware, then 371 ``error_idx`` is less than ``count`` and only the controls up to 372 ``error_idx-1`` were read or written correctly, and the state of 373 the remaining controls is undefined. 374 375 Since :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` does not access hardware there is 376 also no need to handle the validation step in this special way, so 377 ``error_idx`` will just be set to the control that failed the 378 validation step instead of to ``count``. This means that if 379 :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` fails with ``error_idx`` set to ``count``, 380 then you can call :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` to try to discover the 381 actual control that failed the validation step. Unfortunately, 382 there is no ``TRY`` equivalent for :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`. 383 * - __s32 384 - ``request_fd`` 385 - File descriptor of the request to be used by this operation. Only 386 valid if ``which`` is set to ``V4L2_CTRL_WHICH_REQUEST_VAL``. 387 If the device does not support requests, then ``EACCES`` will be returned. 388 If requests are supported but an invalid request file descriptor is 389 given, then ``EINVAL`` will be returned. 390 * - __u32 391 - ``reserved``\ [1] 392 - Reserved for future extensions. 393 394 Drivers and applications must set the array to zero. 395 * - struct :c:type:`v4l2_ext_control` * 396 - ``controls`` 397 - Pointer to an array of ``count`` v4l2_ext_control structures. 398 399 Ignored if ``count`` equals zero. 400 401.. tabularcolumns:: |p{7.3cm}|p{2.0cm}|p{8.0cm}| 402 403.. cssclass:: longtable 404 405.. _ctrl-class: 406 407.. flat-table:: Control classes 408 :header-rows: 0 409 :stub-columns: 0 410 :widths: 3 1 4 411 412 * - ``V4L2_CTRL_CLASS_USER`` 413 - 0x980000 414 - The class containing user controls. These controls are described 415 in :ref:`control`. All controls that can be set using the 416 :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` and 417 :ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` ioctl belong to this 418 class. 419 * - ``V4L2_CTRL_CLASS_CODEC`` 420 - 0x990000 421 - The class containing stateful codec controls. These controls are 422 described in :ref:`codec-controls`. 423 * - ``V4L2_CTRL_CLASS_CAMERA`` 424 - 0x9a0000 425 - The class containing camera controls. These controls are described 426 in :ref:`camera-controls`. 427 * - ``V4L2_CTRL_CLASS_FM_TX`` 428 - 0x9b0000 429 - The class containing FM Transmitter (FM TX) controls. These 430 controls are described in :ref:`fm-tx-controls`. 431 * - ``V4L2_CTRL_CLASS_FLASH`` 432 - 0x9c0000 433 - The class containing flash device controls. These controls are 434 described in :ref:`flash-controls`. 435 * - ``V4L2_CTRL_CLASS_JPEG`` 436 - 0x9d0000 437 - The class containing JPEG compression controls. These controls are 438 described in :ref:`jpeg-controls`. 439 * - ``V4L2_CTRL_CLASS_IMAGE_SOURCE`` 440 - 0x9e0000 441 - The class containing image source controls. These controls are 442 described in :ref:`image-source-controls`. 443 * - ``V4L2_CTRL_CLASS_IMAGE_PROC`` 444 - 0x9f0000 445 - The class containing image processing controls. These controls are 446 described in :ref:`image-process-controls`. 447 * - ``V4L2_CTRL_CLASS_FM_RX`` 448 - 0xa10000 449 - The class containing FM Receiver (FM RX) controls. These controls 450 are described in :ref:`fm-rx-controls`. 451 * - ``V4L2_CTRL_CLASS_RF_TUNER`` 452 - 0xa20000 453 - The class containing RF tuner controls. These controls are 454 described in :ref:`rf-tuner-controls`. 455 * - ``V4L2_CTRL_CLASS_DETECT`` 456 - 0xa30000 457 - The class containing motion or object detection controls. These controls 458 are described in :ref:`detect-controls`. 459 * - ``V4L2_CTRL_CLASS_CODEC_STATELESS`` 460 - 0xa40000 461 - The class containing stateless codec controls. These controls are 462 described in :ref:`codec-stateless-controls`. 463 * - ``V4L2_CTRL_CLASS_COLORIMETRY`` 464 - 0xa50000 465 - The class containing colorimetry controls. These controls are 466 described in :ref:`colorimetry-controls`. 467 468Return Value 469============ 470 471On success 0 is returned, on error -1 and the ``errno`` variable is set 472appropriately. The generic error codes are described at the 473:ref:`Generic Error Codes <gen-errors>` chapter. 474 475EINVAL 476 The struct :c:type:`v4l2_ext_control` ``id`` is 477 invalid, or the struct :c:type:`v4l2_ext_controls` 478 ``which`` is invalid, or the struct 479 :c:type:`v4l2_ext_control` ``value`` was 480 inappropriate (e.g. the given menu index is not supported by the 481 driver), or the ``which`` field was set to ``V4L2_CTRL_WHICH_REQUEST_VAL`` 482 but the given ``request_fd`` was invalid or ``V4L2_CTRL_WHICH_REQUEST_VAL`` 483 is not supported by the kernel. 484 This error code is also returned by the 485 :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctls if two or 486 more control values are in conflict. 487 488ERANGE 489 The struct :c:type:`v4l2_ext_control` ``value`` 490 is out of bounds. 491 492EBUSY 493 The control is temporarily not changeable, possibly because another 494 applications took over control of the device function this control 495 belongs to, or (if the ``which`` field was set to 496 ``V4L2_CTRL_WHICH_REQUEST_VAL``) the request was queued but not yet 497 completed. 498 499ENOSPC 500 The space reserved for the control's payload is insufficient. The 501 field ``size`` is set to a value that is enough to store the payload 502 and this error code is returned. 503 504EACCES 505 Attempt to try or set a read-only control, or to get a write-only 506 control, or to get a control from a request that has not yet been 507 completed. 508 509 Or the ``which`` field was set to ``V4L2_CTRL_WHICH_REQUEST_VAL`` but the 510 device does not support requests. 511 512 Or if there is an attempt to set an inactive control and the driver is 513 not capable of caching the new value until the control is active again. 514