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Diffstat (limited to 'Documentation/userspace-api/media/v4l/vidioc-g-std.rst')
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diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-std.rst b/Documentation/userspace-api/media/v4l/vidioc-g-std.rst new file mode 100644 index 000000000000..6d8cb7f29ac6 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-g-std.rst @@ -0,0 +1,87 @@ +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/userspace-api/media/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections + +.. _VIDIOC_G_STD: + +************************************************************************** +ioctl VIDIOC_G_STD, VIDIOC_S_STD, VIDIOC_SUBDEV_G_STD, VIDIOC_SUBDEV_S_STD +************************************************************************** + +Name +==== + +VIDIOC_G_STD - VIDIOC_S_STD - VIDIOC_SUBDEV_G_STD - VIDIOC_SUBDEV_S_STD - Query or select the video standard of the current input + + +Synopsis +======== + +.. c:function:: int ioctl( int fd, VIDIOC_G_STD, v4l2_std_id *argp ) + :name: VIDIOC_G_STD + +.. c:function:: int ioctl( int fd, VIDIOC_S_STD, const v4l2_std_id *argp ) + :name: VIDIOC_S_STD + +.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_STD, v4l2_std_id *argp ) + :name: VIDIOC_SUBDEV_G_STD + +.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_STD, const v4l2_std_id *argp ) + :name: VIDIOC_SUBDEV_S_STD + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <func-open>`. + +``argp`` + Pointer to :c:type:`v4l2_std_id`. + + +Description +=========== + +To query and select the current video standard applications use the +:ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a +:ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` +can return a single flag or a set of flags as in struct +:c:type:`v4l2_standard` field ``id``. The flags must be +unambiguous such that they appear in only one enumerated +struct :c:type:`v4l2_standard` structure. + +:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` accepts one or more flags, being a write-only ioctl it +does not return the actual new standard as :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` does. When +no flags are given or the current input does not support the requested +standard the driver returns an ``EINVAL`` error code. When the standard set +is ambiguous drivers may return ``EINVAL`` or choose any of the requested +standards. If the current input or output does not support standard +video timings (e.g. if :ref:`VIDIOC_ENUMINPUT` +does not set the ``V4L2_IN_CAP_STD`` flag), then ``ENODATA`` error code is +returned. + +Calling ``VIDIOC_SUBDEV_S_STD`` on a subdev device node that has been registered +in read-only mode is not allowed. An error is returned and the errno variable is +set to ``-EPERM``. + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +EINVAL + The :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` parameter was unsuitable. + +ENODATA + Standard video timings are not supported for this input or output. + +EPERM + ``VIDIOC_SUBDEV_S_STD`` has been called on a read-only subdevice. |