1.. Permission is granted to copy, distribute and/or modify this 2.. document under the terms of the GNU Free Documentation License, 3.. Version 1.1 or any later version published by the Free Software 4.. Foundation, with no Invariant Sections, no Front-Cover Texts 5.. and no Back-Cover Texts. A copy of the license is included at 6.. Documentation/userspace-api/media/fdl-appendix.rst. 7.. 8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections 9 10.. _VIDIOC_SUBDEV_G_SELECTION: 11 12********************************************************** 13ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION 14********************************************************** 15 16Name 17==== 18 19VIDIOC_SUBDEV_G_SELECTION - VIDIOC_SUBDEV_S_SELECTION - Get or set selection rectangles on a subdev pad 20 21 22Synopsis 23======== 24 25.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_SELECTION, struct v4l2_subdev_selection *argp ) 26 :name: VIDIOC_SUBDEV_G_SELECTION 27 28.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_SELECTION, struct v4l2_subdev_selection *argp ) 29 :name: VIDIOC_SUBDEV_S_SELECTION 30 31 32Arguments 33========= 34 35``fd`` 36 File descriptor returned by :ref:`open() <func-open>`. 37 38``argp`` 39 Pointer to struct :c:type:`v4l2_subdev_selection`. 40 41 42Description 43=========== 44 45The selections are used to configure various image processing 46functionality performed by the subdevs which affect the image size. This 47currently includes cropping, scaling and composition. 48 49The selection API replaces 50:ref:`the old subdev crop API <VIDIOC_SUBDEV_G_CROP>`. All the 51function of the crop API, and more, are supported by the selections API. 52 53See :ref:`subdev` for more information on how each selection target 54affects the image processing pipeline inside the subdevice. 55 56If the subdev device node has been registered in read-only mode, calls to 57``VIDIOC_SUBDEV_S_SELECTION`` are only valid if the ``which`` field is set to 58``V4L2_SUBDEV_FORMAT_TRY``, otherwise an error is returned and the errno 59variable is set to ``-EPERM``. 60 61Types of selection targets 62-------------------------- 63 64There are two types of selection targets: actual and bounds. The actual 65targets are the targets which configure the hardware. The BOUNDS target 66will return a rectangle that contain all possible actual rectangles. 67 68 69Discovering supported features 70------------------------------ 71 72To discover which targets are supported, the user can perform 73``VIDIOC_SUBDEV_G_SELECTION`` on them. Any unsupported target will 74return ``EINVAL``. 75 76Selection targets and flags are documented in 77:ref:`v4l2-selections-common`. 78 79 80.. c:type:: v4l2_subdev_selection 81 82.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| 83 84.. flat-table:: struct v4l2_subdev_selection 85 :header-rows: 0 86 :stub-columns: 0 87 :widths: 1 1 2 88 89 * - __u32 90 - ``which`` 91 - Active or try selection, from enum 92 :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`. 93 * - __u32 94 - ``pad`` 95 - Pad number as reported by the media framework. 96 * - __u32 97 - ``target`` 98 - Target selection rectangle. See :ref:`v4l2-selections-common`. 99 * - __u32 100 - ``flags`` 101 - Flags. See :ref:`v4l2-selection-flags`. 102 * - struct :c:type:`v4l2_rect` 103 - ``r`` 104 - Selection rectangle, in pixels. 105 * - __u32 106 - ``reserved``\ [8] 107 - Reserved for future extensions. Applications and drivers must set 108 the array to zero. 109 110 111Return Value 112============ 113 114On success 0 is returned, on error -1 and the ``errno`` variable is set 115appropriately. The generic error codes are described at the 116:ref:`Generic Error Codes <gen-errors>` chapter. 117 118EBUSY 119 The selection rectangle can't be changed because the pad is 120 currently busy. This can be caused, for instance, by an active video 121 stream on the pad. The ioctl must not be retried without performing 122 another action to fix the problem first. Only returned by 123 ``VIDIOC_SUBDEV_S_SELECTION`` 124 125EINVAL 126 The struct :c:type:`v4l2_subdev_selection` 127 ``pad`` references a non-existing pad, the ``which`` field 128 references a non-existing format, or the selection target is not 129 supported on the given subdev pad. 130 131EPERM 132 The ``VIDIOC_SUBDEV_S_SELECTION`` ioctl has been called on a read-only 133 subdevice and the ``which`` field is set to ``V4L2_SUBDEV_FORMAT_ACTIVE``. 134