mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-28 11:18:45 +07:00
b7e67f6c1b
The c language parser checks if there are duplicated object definitions. That causes lots of warnings like: WARNING: duplicate C object description of ioctl Let's remove those by telling Sphinx that the language for those objects are c++. The look of the descriptions will be close, and the warnings will be gone. Please notice that we had to keep a few of them as C, as the c++ parser seems to be broken when it finds an enum. Yet, this reduced from 219 warnings to 143, with is a good thing. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
74 lines
2.3 KiB
ReStructuredText
74 lines
2.3 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
|
|
|
|
.. _VIDIOC_QUERYSTD:
|
|
|
|
*********************
|
|
ioctl VIDIOC_QUERYSTD
|
|
*********************
|
|
|
|
*man VIDIOC_QUERYSTD(2)*
|
|
|
|
Sense the video standard received by the current input
|
|
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. cpp:function:: int ioctl( int fd, int request, v4l2_std_id *argp )
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by :ref:`open() <func-open>`.
|
|
|
|
``request``
|
|
VIDIOC_QUERYSTD
|
|
|
|
``argp``
|
|
|
|
|
|
Description
|
|
===========
|
|
|
|
The hardware may be able to detect the current video standard
|
|
automatically. To do so, applications call :ref:`VIDIOC_QUERYSTD` with a
|
|
pointer to a :ref:`v4l2_std_id <v4l2-std-id>` type. The driver
|
|
stores here a set of candidates, this can be a single flag or a set of
|
|
supported standards if for example the hardware can only distinguish
|
|
between 50 and 60 Hz systems. If no signal was detected, then the driver
|
|
will return V4L2_STD_UNKNOWN. When detection is not possible or fails,
|
|
the set must contain all standards supported by the current video input
|
|
or output.
|
|
|
|
Please note that drivers shall *not* switch the video standard
|
|
automatically if a new video standard is detected. Instead, drivers
|
|
should send the ``V4L2_EVENT_SOURCE_CHANGE`` event (if they support
|
|
this) and expect that userspace will take action by calling
|
|
:ref:`VIDIOC_QUERYSTD`. The reason is that a new video standard can mean
|
|
different buffer sizes as well, and you cannot change buffer sizes on
|
|
the fly. In general, applications that receive the Source Change event
|
|
will have to call :ref:`VIDIOC_QUERYSTD`, and if the detected video
|
|
standard is valid they will have to stop streaming, set the new
|
|
standard, allocate new buffers and start streaming again.
|
|
|
|
|
|
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.
|
|
|
|
ENODATA
|
|
Standard video timings are not supported for this input or output.
|
|
|
|
|
|
.. ------------------------------------------------------------------------------
|
|
.. This file was automatically converted from DocBook-XML with the dbxml
|
|
.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
|
|
.. from the linux kernel, refer to:
|
|
..
|
|
.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
|
|
.. ------------------------------------------------------------------------------
|