xref: /OK3568_Linux_fs/kernel/Documentation/userspace-api/media/v4l/vidioc-log-status.rst (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593Smuzhiyun.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2*4882a593Smuzhiyun.. c:namespace:: V4L
3*4882a593Smuzhiyun
4*4882a593Smuzhiyun.. _VIDIOC_LOG_STATUS:
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun***********************
7*4882a593Smuzhiyunioctl VIDIOC_LOG_STATUS
8*4882a593Smuzhiyun***********************
9*4882a593Smuzhiyun
10*4882a593SmuzhiyunName
11*4882a593Smuzhiyun====
12*4882a593Smuzhiyun
13*4882a593SmuzhiyunVIDIOC_LOG_STATUS - Log driver status information
14*4882a593Smuzhiyun
15*4882a593SmuzhiyunSynopsis
16*4882a593Smuzhiyun========
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun.. c:macro:: VIDIOC_LOG_STATUS
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun``int ioctl(int fd, VIDIOC_LOG_STATUS)``
21*4882a593Smuzhiyun
22*4882a593SmuzhiyunArguments
23*4882a593Smuzhiyun=========
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun``fd``
26*4882a593Smuzhiyun    File descriptor returned by :c:func:`open()`.
27*4882a593Smuzhiyun
28*4882a593SmuzhiyunDescription
29*4882a593Smuzhiyun===========
30*4882a593Smuzhiyun
31*4882a593SmuzhiyunAs the video/audio devices become more complicated it becomes harder to
32*4882a593Smuzhiyundebug problems. When this ioctl is called the driver will output the
33*4882a593Smuzhiyuncurrent device status to the kernel log. This is particular useful when
34*4882a593Smuzhiyundealing with problems like no sound, no video and incorrectly tuned
35*4882a593Smuzhiyunchannels. Also many modern devices autodetect video and audio standards
36*4882a593Smuzhiyunand this ioctl will report what the device thinks what the standard is.
37*4882a593SmuzhiyunMismatches may give an indication where the problem is.
38*4882a593Smuzhiyun
39*4882a593SmuzhiyunThis ioctl is optional and not all drivers support it. It was introduced
40*4882a593Smuzhiyunin Linux 2.6.15.
41*4882a593Smuzhiyun
42*4882a593SmuzhiyunReturn Value
43*4882a593Smuzhiyun============
44*4882a593Smuzhiyun
45*4882a593SmuzhiyunOn success 0 is returned, on error -1 and the ``errno`` variable is set
46*4882a593Smuzhiyunappropriately. The generic error codes are described at the
47*4882a593Smuzhiyun:ref:`Generic Error Codes <gen-errors>` chapter.
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