1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 .. c:namespace:: V4L
3
4 .. _VIDIOC_SUBDEV_G_CROP:
5
6 ************************************************
7 ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP
8 ************************************************
9
10 Name
11 ====
12
13 VIDIOC_SUBDEV_G_CROP - VIDIOC_SUBDEV_S_CROP - Get or set the crop rectangle on a subdev pad
14
15 Synopsis
16 ========
17
18 .. c:macro:: VIDIOC_SUBDEV_G_CROP
19
20 ``int ioctl(int fd, VIDIOC_SUBDEV_G_CROP, struct v4l2_subdev_crop *argp)``
21
22 .. c:macro:: VIDIOC_SUBDEV_S_CROP
23
24 ``int ioctl(int fd, VIDIOC_SUBDEV_S_CROP, const struct v4l2_subdev_crop *argp)``
25
26 Arguments
27 =========
28
29 ``fd``
30 File descriptor returned by :c:func:`open()`.
31
32 ``argp``
33 Pointer to struct :c:type:`v4l2_subdev_crop`.
34
35 Description
36 ===========
37
38 .. note::
39
40 This is an :ref:`obsolete` interface and may be removed in the future. It is
41 superseded by :ref:`the selection API <VIDIOC_SUBDEV_G_SELECTION>`. No new
42 extensions to the :c:type:`v4l2_subdev_crop` structure will be accepted.
43
44 To retrieve the current crop rectangle applications set the ``pad``
45 field of a struct :c:type:`v4l2_subdev_crop` to the
46 desired pad number as reported by the media API and the ``which`` field
47 to ``V4L2_SUBDEV_FORMAT_ACTIVE``. They then call the
48 ``VIDIOC_SUBDEV_G_CROP`` ioctl with a pointer to this structure. The
49 driver fills the members of the ``rect`` field or returns ``EINVAL`` error
50 code if the input arguments are invalid, or if cropping is not supported
51 on the given pad.
52
53 To change the current crop rectangle applications set both the ``pad``
54 and ``which`` fields and all members of the ``rect`` field. They then
55 call the ``VIDIOC_SUBDEV_S_CROP`` ioctl with a pointer to this
56 structure. The driver verifies the requested crop rectangle, adjusts it
57 based on the hardware capabilities and configures the device. Upon
58 return the struct :c:type:`v4l2_subdev_crop`
59 contains the current format as would be returned by a
60 ``VIDIOC_SUBDEV_G_CROP`` call.
61
62 Applications can query the device capabilities by setting the ``which``
63 to ``V4L2_SUBDEV_FORMAT_TRY``. When set, 'try' crop rectangles are not
64 applied to the device by the driver, but are mangled exactly as active
65 crop rectangles and stored in the sub-device file handle. Two
66 applications querying the same sub-device would thus not interact with
67 each other.
68
69 If the subdev device node has been registered in read-only mode, calls to
70 ``VIDIOC_SUBDEV_S_CROP`` are only valid if the ``which`` field is set to
71 ``V4L2_SUBDEV_FORMAT_TRY``, otherwise an error is returned and the errno
72 variable is set to ``-EPERM``.
73
74 Drivers must not return an error solely because the requested crop
75 rectangle doesn't match the device capabilities. They must instead
76 modify the rectangle to match what the hardware can provide. The
77 modified format should be as close as possible to the original request.
78
79 .. c:type:: v4l2_subdev_crop
80
81 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
82
83 .. flat-table:: struct v4l2_subdev_crop
84 :header-rows: 0
85 :stub-columns: 0
86 :widths: 1 1 2
87
88 * - __u32
89 - ``pad``
90 - Pad number as reported by the media framework.
91 * - __u32
92 - ``which``
93 - Crop rectangle to get or set, from enum
94 :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
95 * - struct :c:type:`v4l2_rect`
96 - ``rect``
97 - Crop rectangle boundaries, in pixels.
98 * - __u32
99 - ``stream``
100 - Stream identifier.
101 * - __u32
102 - ``reserved``\ [7]
103 - Reserved for future extensions. Applications and drivers must set
104 the array to zero.
105
106 Return Value
107 ============
108
109 On success 0 is returned, on error -1 and the ``errno`` variable is set
110 appropriately. The generic error codes are described at the
111 :ref:`Generic Error Codes <gen-errors>` chapter.
112
113 EBUSY
114 The crop rectangle can't be changed because the pad is currently
115 busy. This can be caused, for instance, by an active video stream on
116 the pad. The ioctl must not be retried without performing another
117 action to fix the problem first. Only returned by
118 ``VIDIOC_SUBDEV_S_CROP``
119
120 EINVAL
121 The struct :c:type:`v4l2_subdev_crop` ``pad`` references a non-existing pad,
122 the ``which`` field has an unsupported value, or cropping is not supported
123 on the given subdev pad.
124
125 EPERM
126 The ``VIDIOC_SUBDEV_S_CROP`` ioctl has been called on a read-only subdevice
127 and the ``which`` field is set to ``V4L2_SUBDEV_FORMAT_ACTIVE``.
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