1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 .. c:namespace:: V4L
3
4 .. _VIDIOC_SUBDEV_ENUM_FRAME_SIZE:
5
6 ***********************************
7 ioctl VIDIOC_SUBDEV_ENUM_FRAME_SIZE
8 ***********************************
9
10 Name
11 ====
12
13 VIDIOC_SUBDEV_ENUM_FRAME_SIZE - Enumerate media bus frame sizes
14
15 Synopsis
16 ========
17
18 .. c:macro:: VIDIOC_SUBDEV_ENUM_FRAME_SIZE
19
20 ``int ioctl(int fd, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, struct v4l2_subdev_frame_size_enum * argp)``
21
22 Arguments
23 =========
24
25 ``fd``
26 File descriptor returned by :c:func:`open()`.
27
28 ``argp``
29 Pointer to struct :c:type:`v4l2_subdev_frame_size_enum`.
30
31 Description
32 ===========
33
34 This ioctl allows applications to access the enumeration of frame sizes
35 supported by a sub-device on the specified pad
36 for the specified media bus format.
37 Supported formats can be retrieved with the
38 :ref:`VIDIOC_SUBDEV_ENUM_MBUS_CODE`
39 ioctl.
40
41 The enumerations are defined by the driver, and indexed using the ``index`` field
42 of the struct :c:type:`v4l2_subdev_frame_size_enum`.
43 Each pair of ``pad`` and ``code`` correspond to a separate enumeration.
44 Each enumeration starts with the ``index`` of 0, and
45 the lowest invalid index marks the end of the enumeration.
46
47 Therefore, to enumerate frame sizes allowed on the specified pad
48 and using the specified mbus format, initialize the
49 ``pad``, ``which``, and ``code`` fields to desired values,
50 and set ``index`` to 0.
51 Then call the :ref:`VIDIOC_SUBDEV_ENUM_FRAME_SIZE` ioctl with a pointer to the
52 structure.
53
54 A successful call will return with minimum and maximum frame sizes filled in.
55 Repeat with increasing ``index`` until ``EINVAL`` is received.
56 ``EINVAL`` means that either no more entries are available in the enumeration,
57 or that an input parameter was invalid.
58
59 Sub-devices that only support discrete frame sizes (such as most
60 sensors) will return one or more frame sizes with identical minimum and
61 maximum values.
62
63 Not all possible sizes in given [minimum, maximum] ranges need to be
64 supported. For instance, a scaler that uses a fixed-point scaling ratio
65 might not be able to produce every frame size between the minimum and
66 maximum values. Applications must use the
67 :ref:`VIDIOC_SUBDEV_S_FMT <VIDIOC_SUBDEV_G_FMT>` ioctl to try the
68 sub-device for an exact supported frame size.
69
70 Available frame sizes may depend on the current 'try' formats at other
71 pads of the sub-device, as well as on the current active links and the
72 current values of V4L2 controls. See
73 :ref:`VIDIOC_SUBDEV_G_FMT` for more
74 information about try formats.
75
76 .. c:type:: v4l2_subdev_frame_size_enum
77
78 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
79
80 .. flat-table:: struct v4l2_subdev_frame_size_enum
81 :header-rows: 0
82 :stub-columns: 0
83 :widths: 1 1 2
84
85 * - __u32
86 - ``index``
87 - Index of the frame size in the enumeration belonging to the given pad
88 and format. Filled in by the application.
89 * - __u32
90 - ``pad``
91 - Pad number as reported by the media controller API.
92 Filled in by the application.
93 * - __u32
94 - ``code``
95 - The media bus format code, as defined in
96 :ref:`v4l2-mbus-format`. Filled in by the application.
97 * - __u32
98 - ``min_width``
99 - Minimum frame width, in pixels. Filled in by the driver.
100 * - __u32
101 - ``max_width``
102 - Maximum frame width, in pixels. Filled in by the driver.
103 * - __u32
104 - ``min_height``
105 - Minimum frame height, in pixels. Filled in by the driver.
106 * - __u32
107 - ``max_height``
108 - Maximum frame height, in pixels. Filled in by the driver.
109 * - __u32
110 - ``which``
111 - Frame sizes to be enumerated, from enum
112 :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
113 * - __u32
114 - ``stream``
115 - Stream identifier.
116 * - __u32
117 - ``reserved``\ [7]
118 - Reserved for future extensions. Applications and drivers must set
119 the array to zero.
120
121 Return Value
122 ============
123
124 On success 0 is returned, on error -1 and the ``errno`` variable is set
125 appropriately. The generic error codes are described at the
126 :ref:`Generic Error Codes <gen-errors>` chapter.
127
128 EINVAL
129 The struct :c:type:`v4l2_subdev_frame_size_enum` ``pad`` references a
130 non-existing pad, the ``which`` field has an unsupported value, the ``code``
131 is invalid for the given pad, or the ``index`` field is out of bounds.
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