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1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
af4a4d0d | 3 | .. _VIDIOC_SUBDEV_G_FRAME_INTERVAL: |
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4 | |
5 | ******************************************************************** | |
6 | ioctl VIDIOC_SUBDEV_G_FRAME_INTERVAL, VIDIOC_SUBDEV_S_FRAME_INTERVAL | |
7 | ******************************************************************** | |
8 | ||
9 | *man VIDIOC_SUBDEV_G_FRAME_INTERVAL(2)* | |
10 | ||
11 | VIDIOC_SUBDEV_S_FRAME_INTERVAL | |
12 | Get or set the frame interval on a subdev pad | |
13 | ||
14 | ||
15 | Synopsis | |
16 | ======== | |
17 | ||
b7e67f6c | 18 | .. cpp:function:: int ioctl( int fd, int request, struct v4l2_subdev_frame_interval *argp ) |
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19 | |
20 | Arguments | |
21 | ========= | |
22 | ||
23 | ``fd`` | |
24 | File descriptor returned by :ref:`open() <func-open>`. | |
25 | ||
26 | ``request`` | |
27 | VIDIOC_SUBDEV_G_FRAME_INTERVAL, | |
28 | VIDIOC_SUBDEV_S_FRAME_INTERVAL | |
29 | ||
30 | ``argp`` | |
31 | ||
32 | ||
33 | Description | |
34 | =========== | |
35 | ||
36 | These ioctls are used to get and set the frame interval at specific | |
37 | subdev pads in the image pipeline. The frame interval only makes sense | |
38 | for sub-devices that can control the frame period on their own. This | |
39 | includes, for instance, image sensors and TV tuners. Sub-devices that | |
40 | don't support frame intervals must not implement these ioctls. | |
41 | ||
42 | To retrieve the current frame interval applications set the ``pad`` | |
43 | field of a struct | |
44 | :ref:`v4l2_subdev_frame_interval <v4l2-subdev-frame-interval>` to | |
45 | the desired pad number as reported by the media controller API. When | |
46 | they call the ``VIDIOC_SUBDEV_G_FRAME_INTERVAL`` ioctl with a pointer to | |
47 | this structure the driver fills the members of the ``interval`` field. | |
48 | ||
49 | To change the current frame interval applications set both the ``pad`` | |
50 | field and all members of the ``interval`` field. When they call the | |
51 | ``VIDIOC_SUBDEV_S_FRAME_INTERVAL`` ioctl with a pointer to this | |
52 | structure the driver verifies the requested interval, adjusts it based | |
53 | on the hardware capabilities and configures the device. Upon return the | |
54 | struct | |
55 | :ref:`v4l2_subdev_frame_interval <v4l2-subdev-frame-interval>` | |
56 | contains the current frame interval as would be returned by a | |
57 | ``VIDIOC_SUBDEV_G_FRAME_INTERVAL`` call. | |
58 | ||
59 | Drivers must not return an error solely because the requested interval | |
60 | doesn't match the device capabilities. They must instead modify the | |
61 | interval to match what the hardware can provide. The modified interval | |
62 | should be as close as possible to the original request. | |
63 | ||
64 | Sub-devices that support the frame interval ioctls should implement them | |
65 | on a single pad only. Their behaviour when supported on multiple pads of | |
66 | the same sub-device is not defined. | |
67 | ||
68 | ||
69 | .. _v4l2-subdev-frame-interval: | |
70 | ||
71 | .. flat-table:: struct v4l2_subdev_frame_interval | |
72 | :header-rows: 0 | |
73 | :stub-columns: 0 | |
74 | :widths: 1 1 2 | |
75 | ||
76 | ||
77 | - .. row 1 | |
78 | ||
79 | - __u32 | |
80 | ||
81 | - ``pad`` | |
82 | ||
83 | - Pad number as reported by the media controller API. | |
84 | ||
85 | - .. row 2 | |
86 | ||
87 | - struct :ref:`v4l2_fract <v4l2-fract>` | |
88 | ||
89 | - ``interval`` | |
90 | ||
91 | - Period, in seconds, between consecutive video frames. | |
92 | ||
93 | - .. row 3 | |
94 | ||
95 | - __u32 | |
96 | ||
97 | - ``reserved``\ [9] | |
98 | ||
99 | - Reserved for future extensions. Applications and drivers must set | |
100 | the array to zero. | |
101 | ||
102 | ||
103 | ||
104 | Return Value | |
105 | ============ | |
106 | ||
107 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
108 | appropriately. The generic error codes are described at the | |
109 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
110 | ||
111 | EBUSY | |
112 | The frame interval can't be changed because the pad is currently | |
113 | busy. This can be caused, for instance, by an active video stream on | |
114 | the pad. The ioctl must not be retried without performing another | |
115 | action to fix the problem first. Only returned by | |
116 | ``VIDIOC_SUBDEV_S_FRAME_INTERVAL`` | |
117 | ||
118 | EINVAL | |
119 | The struct | |
120 | :ref:`v4l2_subdev_frame_interval <v4l2-subdev-frame-interval>` | |
121 | ``pad`` references a non-existing pad, or the pad doesn't support | |
122 | frame intervals. | |
123 | ||
124 | ||
125 | .. ------------------------------------------------------------------------------ | |
126 | .. This file was automatically converted from DocBook-XML with the dbxml | |
127 | .. library (https://github.com/return42/sphkerneldoc). The origin XML comes | |
128 | .. from the linux kernel, refer to: | |
129 | .. | |
130 | .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook | |
131 | .. ------------------------------------------------------------------------------ |