1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
4 .. _VIDIOC_SUBDEV_G_SELECTION:
6 **********************************************************
7 ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION
8 **********************************************************
13 VIDIOC_SUBDEV_G_SELECTION - VIDIOC_SUBDEV_S_SELECTION - Get or set selection rectangles on a subdev pad
18 .. c:macro:: VIDIOC_SUBDEV_G_SELECTION
20 ``int ioctl(int fd, VIDIOC_SUBDEV_G_SELECTION, struct v4l2_subdev_selection *argp)``
22 .. c:macro:: VIDIOC_SUBDEV_S_SELECTION
24 ``int ioctl(int fd, VIDIOC_SUBDEV_S_SELECTION, struct v4l2_subdev_selection *argp)``
30 File descriptor returned by :c:func:`open()`.
33 Pointer to struct :c:type:`v4l2_subdev_selection`.
38 The selections are used to configure various image processing
39 functionality performed by the subdevs which affect the image size. This
40 currently includes cropping, scaling and composition.
42 The selection API replaces
43 :ref:`the old subdev crop API <VIDIOC_SUBDEV_G_CROP>`. All the
44 function of the crop API, and more, are supported by the selections API.
46 See :ref:`subdev` for more information on how each selection target
47 affects the image processing pipeline inside the subdevice.
49 If 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
52 variable is set to ``-EPERM``.
54 Types of selection targets
55 --------------------------
57 There are two types of selection targets: actual and bounds. The actual
58 targets are the targets which configure the hardware. The BOUNDS target
59 will return a rectangle that contain all possible actual rectangles.
61 Discovering supported features
62 ------------------------------
64 To discover which targets are supported, the user can perform
65 ``VIDIOC_SUBDEV_G_SELECTION`` on them. Any unsupported target will
68 Selection targets and flags are documented in
69 :ref:`v4l2-selections-common`.
71 .. c:type:: v4l2_subdev_selection
73 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
75 .. flat-table:: struct v4l2_subdev_selection
82 - Active or try selection, from enum
83 :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
86 - Pad number as reported by the media framework.
89 - Target selection rectangle. See :ref:`v4l2-selections-common`.
92 - Flags. See :ref:`v4l2-selection-flags`.
93 * - struct :c:type:`v4l2_rect`
95 - Selection rectangle, in pixels.
98 - Reserved for future extensions. Applications and drivers must set
104 On success 0 is returned, on error -1 and the ``errno`` variable is set
105 appropriately. The generic error codes are described at the
106 :ref:`Generic Error Codes <gen-errors>` chapter.
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``
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.
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``.