| David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame^] | 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/media/uapi/fdl-appendix.rst. |
| 7 | .. |
| 8 | .. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 9 | |
| 10 | .. _VIDIOC_G_INPUT: |
| 11 | |
| 12 | ************************************ |
| 13 | ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT |
| 14 | ************************************ |
| 15 | |
| 16 | Name |
| 17 | ==== |
| 18 | |
| 19 | VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input |
| 20 | |
| 21 | |
| 22 | Synopsis |
| 23 | ======== |
| 24 | |
| 25 | .. c:function:: int ioctl( int fd, VIDIOC_G_INPUT, int *argp ) |
| 26 | :name: VIDIOC_G_INPUT |
| 27 | |
| 28 | .. c:function:: int ioctl( int fd, VIDIOC_S_INPUT, int *argp ) |
| 29 | :name: VIDIOC_S_INPUT |
| 30 | |
| 31 | |
| 32 | Arguments |
| 33 | ========= |
| 34 | |
| 35 | ``fd`` |
| 36 | File descriptor returned by :ref:`open() <func-open>`. |
| 37 | |
| 38 | ``argp`` |
| 39 | Pointer an integer with input index. |
| 40 | |
| 41 | |
| 42 | Description |
| 43 | =========== |
| 44 | |
| 45 | To query the current video input applications call the |
| 46 | :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver |
| 47 | stores the number of the input, as in the struct |
| 48 | :c:type:`v4l2_input` ``index`` field. This ioctl will fail |
| 49 | only when there are no video inputs, returning ``EINVAL``. |
| 50 | |
| 51 | To select a video input applications store the number of the desired |
| 52 | input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer |
| 53 | to this integer. Side effects are possible. For example inputs may |
| 54 | support different video standards, so the driver may implicitly switch |
| 55 | the current standard. Because of these possible side effects |
| 56 | applications must select an input before querying or negotiating any |
| 57 | other parameters. |
| 58 | |
| 59 | Information about video inputs is available using the |
| 60 | :ref:`VIDIOC_ENUMINPUT` ioctl. |
| 61 | |
| 62 | |
| 63 | Return Value |
| 64 | ============ |
| 65 | |
| 66 | On success 0 is returned, on error -1 and the ``errno`` variable is set |
| 67 | appropriately. The generic error codes are described at the |
| 68 | :ref:`Generic Error Codes <gen-errors>` chapter. |
| 69 | |
| 70 | EINVAL |
| 71 | The number of the video input is out of bounds. |