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_CROP:
11
12************************************************
13ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP
14************************************************
15
16Name
17====
18
19VIDIOC_SUBDEV_G_CROP - VIDIOC_SUBDEV_S_CROP - Get or set the crop rectangle on a subdev pad
20
21
22Synopsis
23========
24
25.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_CROP, struct v4l2_subdev_crop *argp )
26    :name: VIDIOC_SUBDEV_G_CROP
27
28.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_CROP, const struct v4l2_subdev_crop *argp )
29    :name: VIDIOC_SUBDEV_S_CROP
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_crop`.
40
41
42Description
43===========
44
45.. note::
46
47    This is an :ref:`obsolete` interface and may be removed
48    in the future. It is superseded by
49    :ref:`the selection API <VIDIOC_SUBDEV_G_SELECTION>`.
50
51To retrieve the current crop rectangle applications set the ``pad``
52field of a struct :c:type:`v4l2_subdev_crop` to the
53desired pad number as reported by the media API and the ``which`` field
54to ``V4L2_SUBDEV_FORMAT_ACTIVE``. They then call the
55``VIDIOC_SUBDEV_G_CROP`` ioctl with a pointer to this structure. The
56driver fills the members of the ``rect`` field or returns ``EINVAL`` error
57code if the input arguments are invalid, or if cropping is not supported
58on the given pad.
59
60To change the current crop rectangle applications set both the ``pad``
61and ``which`` fields and all members of the ``rect`` field. They then
62call the ``VIDIOC_SUBDEV_S_CROP`` ioctl with a pointer to this
63structure. The driver verifies the requested crop rectangle, adjusts it
64based on the hardware capabilities and configures the device. Upon
65return the struct :c:type:`v4l2_subdev_crop`
66contains the current format as would be returned by a
67``VIDIOC_SUBDEV_G_CROP`` call.
68
69Applications can query the device capabilities by setting the ``which``
70to ``V4L2_SUBDEV_FORMAT_TRY``. When set, 'try' crop rectangles are not
71applied to the device by the driver, but are mangled exactly as active
72crop rectangles and stored in the sub-device file handle. Two
73applications querying the same sub-device would thus not interact with
74each other.
75
76If the subdev device node has been registered in read-only mode, calls to
77``VIDIOC_SUBDEV_S_CROP`` are only valid if the ``which`` field is set to
78``V4L2_SUBDEV_FORMAT_TRY``, otherwise an error is returned and the errno
79variable is set to ``-EPERM``.
80
81Drivers must not return an error solely because the requested crop
82rectangle doesn't match the device capabilities. They must instead
83modify the rectangle to match what the hardware can provide. The
84modified format should be as close as possible to the original request.
85
86
87.. c:type:: v4l2_subdev_crop
88
89.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
90
91.. flat-table:: struct v4l2_subdev_crop
92    :header-rows:  0
93    :stub-columns: 0
94    :widths:       1 1 2
95
96    * - __u32
97      - ``pad``
98      - Pad number as reported by the media framework.
99    * - __u32
100      - ``which``
101      - Crop rectangle to get or set, from enum
102	:ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
103    * - struct :c:type:`v4l2_rect`
104      - ``rect``
105      - Crop rectangle boundaries, in pixels.
106    * - __u32
107      - ``reserved``\ [8]
108      - Reserved for future extensions. Applications and drivers must set
109	the array to zero.
110
111
112Return Value
113============
114
115On success 0 is returned, on error -1 and the ``errno`` variable is set
116appropriately. The generic error codes are described at the
117:ref:`Generic Error Codes <gen-errors>` chapter.
118
119EBUSY
120    The crop rectangle can't be changed because the pad is currently
121    busy. This can be caused, for instance, by an active video stream on
122    the pad. The ioctl must not be retried without performing another
123    action to fix the problem first. Only returned by
124    ``VIDIOC_SUBDEV_S_CROP``
125
126EINVAL
127    The struct :c:type:`v4l2_subdev_crop` ``pad``
128    references a non-existing pad, the ``which`` field references a
129    non-existing format, or cropping is not supported on the given
130    subdev pad.
131
132EPERM
133    The ``VIDIOC_SUBDEV_S_CROP`` ioctl has been called on a read-only subdevice
134    and the ``which`` field is set to ``V4L2_SUBDEV_FORMAT_ACTIVE``.
135