1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_SUBDEV_G_SELECTION: 5 6********************************************************** 7ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION 8********************************************************** 9 10Name 11==== 12 13VIDIOC_SUBDEV_G_SELECTION - VIDIOC_SUBDEV_S_SELECTION - Get or set selection rectangles on a subdev pad 14 15Synopsis 16======== 17 18.. c:macro:: VIDIOC_SUBDEV_G_SELECTION 19 20``int ioctl(int fd, VIDIOC_SUBDEV_G_SELECTION, struct v4l2_subdev_selection *argp)`` 21 22.. c:macro:: VIDIOC_SUBDEV_S_SELECTION 23 24``int ioctl(int fd, VIDIOC_SUBDEV_S_SELECTION, struct v4l2_subdev_selection *argp)`` 25 26Arguments 27========= 28 29``fd`` 30 File descriptor returned by :c:func:`open()`. 31 32``argp`` 33 Pointer to struct :c:type:`v4l2_subdev_selection`. 34 35Description 36=========== 37 38The selections are used to configure various image processing 39functionality performed by the subdevs which affect the image size. This 40currently includes cropping, scaling and composition. 41 42The selection API replaces 43:ref:`the old subdev crop API <VIDIOC_SUBDEV_G_CROP>`. All the 44function of the crop API, and more, are supported by the selections API. 45 46See :ref:`subdev` for more information on how each selection target 47affects the image processing pipeline inside the subdevice. 48 49If the subdev device node has been registered in read-only mode, calls to 50``VIDIOC_SUBDEV_S_SELECTION`` are only valid if the ``which`` field is set to 51``V4L2_SUBDEV_FORMAT_TRY``, otherwise an error is returned and the errno 52variable is set to ``-EPERM``. 53 54Types of selection targets 55-------------------------- 56 57There are two types of selection targets: actual and bounds. The actual 58targets are the targets which configure the hardware. The BOUNDS target 59will return a rectangle that contain all possible actual rectangles. 60 61Discovering supported features 62------------------------------ 63 64To discover which targets are supported, the user can perform 65``VIDIOC_SUBDEV_G_SELECTION`` on them. Any unsupported target will 66return ``EINVAL``. 67 68Selection targets and flags are documented in 69:ref:`v4l2-selections-common`. 70 71.. c:type:: v4l2_subdev_selection 72 73.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| 74 75.. flat-table:: struct v4l2_subdev_selection 76 :header-rows: 0 77 :stub-columns: 0 78 :widths: 1 1 2 79 80 * - __u32 81 - ``which`` 82 - Active or try selection, from enum 83 :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`. 84 * - __u32 85 - ``pad`` 86 - Pad number as reported by the media framework. 87 * - __u32 88 - ``target`` 89 - Target selection rectangle. See :ref:`v4l2-selections-common`. 90 * - __u32 91 - ``flags`` 92 - Flags. See :ref:`v4l2-selection-flags`. 93 * - struct :c:type:`v4l2_rect` 94 - ``r`` 95 - Selection rectangle, in pixels. 96 * - __u32 97 - ``reserved``\ [8] 98 - Reserved for future extensions. Applications and drivers must set 99 the array to zero. 100 101Return Value 102============ 103 104On success 0 is returned, on error -1 and the ``errno`` variable is set 105appropriately. The generic error codes are described at the 106:ref:`Generic Error Codes <gen-errors>` chapter. 107 108EBUSY 109 The selection rectangle can't be changed because the pad is 110 currently busy. This can be caused, for instance, by an active video 111 stream on the pad. The ioctl must not be retried without performing 112 another action to fix the problem first. Only returned by 113 ``VIDIOC_SUBDEV_S_SELECTION`` 114 115EINVAL 116 The struct :c:type:`v4l2_subdev_selection` 117 ``pad`` references a non-existing pad, the ``which`` field 118 references a non-existing format, or the selection target is not 119 supported on the given subdev pad. 120 121EPERM 122 The ``VIDIOC_SUBDEV_S_SELECTION`` ioctl has been called on a read-only 123 subdevice and the ``which`` field is set to ``V4L2_SUBDEV_FORMAT_ACTIVE``. 124