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Diffstat (limited to 'Documentation/userspace-api/media/v4l/vidioc-enum-dv-timings.rst')
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diff --git a/Documentation/userspace-api/media/v4l/vidioc-enum-dv-timings.rst b/Documentation/userspace-api/media/v4l/vidioc-enum-dv-timings.rst new file mode 100644 index 000000000000..89d6b860193a --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-enum-dv-timings.rst @@ -0,0 +1,114 @@ +.. 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_ENUM_DV_TIMINGS: + +*********************************************************** +ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS +*********************************************************** + +Name +==== + +VIDIOC_ENUM_DV_TIMINGS - VIDIOC_SUBDEV_ENUM_DV_TIMINGS - Enumerate supported Digital Video timings + + +Synopsis +======== + +.. c:function:: int ioctl( int fd, VIDIOC_ENUM_DV_TIMINGS, struct v4l2_enum_dv_timings *argp ) + :name: VIDIOC_ENUM_DV_TIMINGS + +.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_ENUM_DV_TIMINGS, struct v4l2_enum_dv_timings *argp ) + :name: VIDIOC_SUBDEV_ENUM_DV_TIMINGS + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <func-open>`. + +``argp`` + Pointer to struct :c:type:`v4l2_enum_dv_timings`. + + +Description +=========== + +While some DV receivers or transmitters support a wide range of timings, +others support only a limited number of timings. With this ioctl +applications can enumerate a list of known supported timings. Call +:ref:`VIDIOC_DV_TIMINGS_CAP` to check if it +also supports other standards or even custom timings that are not in +this list. + +To query the available timings, applications initialize the ``index`` +field, set the ``pad`` field to 0, zero the reserved array of struct +:c:type:`v4l2_enum_dv_timings` and call the +``VIDIOC_ENUM_DV_TIMINGS`` ioctl on a video node with a pointer to this +structure. Drivers fill the rest of the structure or return an ``EINVAL`` +error code when the index is out of bounds. To enumerate all supported +DV timings, applications shall begin at index zero, incrementing by one +until the driver returns ``EINVAL``. + +.. note:: + + Drivers may enumerate a different set of DV timings after + switching the video input or output. + +When implemented by the driver DV timings of subdevices can be queried +by calling the ``VIDIOC_SUBDEV_ENUM_DV_TIMINGS`` ioctl directly on a +subdevice node. The DV timings are specific to inputs (for DV receivers) +or outputs (for DV transmitters), applications must specify the desired +pad number in the struct +:c:type:`v4l2_enum_dv_timings` ``pad`` field. +Attempts to enumerate timings on a pad that doesn't support them will +return an ``EINVAL`` error code. + + +.. c:type:: v4l2_enum_dv_timings + +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| + +.. flat-table:: struct v4l2_enum_dv_timings + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + * - __u32 + - ``index`` + - Number of the DV timings, set by the application. + * - __u32 + - ``pad`` + - Pad number as reported by the media controller API. This field is + only used when operating on a subdevice node. When operating on a + video node applications must set this field to zero. + * - __u32 + - ``reserved``\ [2] + - Reserved for future extensions. Drivers and applications must set + the array to zero. + * - struct :c:type:`v4l2_dv_timings` + - ``timings`` + - The timings. + + +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 struct :c:type:`v4l2_enum_dv_timings` + ``index`` is out of bounds or the ``pad`` number is invalid. + +ENODATA + Digital video presets are not supported for this input or output. |