xref: /OK3568_Linux_fs/kernel/Documentation/userspace-api/media/dvb/fe-read-status.rst (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593Smuzhiyun.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2*4882a593Smuzhiyun.. c:namespace:: DTV.fe
3*4882a593Smuzhiyun
4*4882a593Smuzhiyun.. _FE_READ_STATUS:
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun********************
7*4882a593Smuzhiyunioctl FE_READ_STATUS
8*4882a593Smuzhiyun********************
9*4882a593Smuzhiyun
10*4882a593SmuzhiyunName
11*4882a593Smuzhiyun====
12*4882a593Smuzhiyun
13*4882a593SmuzhiyunFE_READ_STATUS - Returns status information about the front-end. This call only requires - read-only access to the device
14*4882a593Smuzhiyun
15*4882a593SmuzhiyunSynopsis
16*4882a593Smuzhiyun========
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun.. c:macro:: FE_READ_STATUS
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun``int ioctl(int fd, FE_READ_STATUS, unsigned int *status)``
21*4882a593Smuzhiyun
22*4882a593SmuzhiyunArguments
23*4882a593Smuzhiyun=========
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun``fd``
26*4882a593Smuzhiyun    File descriptor returned by :c:func:`open()`.
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun``status``
29*4882a593Smuzhiyun    pointer to a bitmask integer filled with the values defined by enum
30*4882a593Smuzhiyun    :c:type:`fe_status`.
31*4882a593Smuzhiyun
32*4882a593SmuzhiyunDescription
33*4882a593Smuzhiyun===========
34*4882a593Smuzhiyun
35*4882a593SmuzhiyunAll Digital TV frontend devices support the ``FE_READ_STATUS`` ioctl. It is
36*4882a593Smuzhiyunused to check about the locking status of the frontend after being
37*4882a593Smuzhiyuntuned. The ioctl takes a pointer to an integer where the status will be
38*4882a593Smuzhiyunwritten.
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun.. note::
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun   The size of status is actually sizeof(enum fe_status), with
43*4882a593Smuzhiyun   varies according with the architecture. This needs to be fixed in the
44*4882a593Smuzhiyun   future.
45*4882a593Smuzhiyun
46*4882a593Smuzhiyunint fe_status
47*4882a593Smuzhiyun=============
48*4882a593Smuzhiyun
49*4882a593SmuzhiyunThe fe_status parameter is used to indicate the current state and/or
50*4882a593Smuzhiyunstate changes of the frontend hardware. It is produced using the enum
51*4882a593Smuzhiyun:c:type:`fe_status` values on a bitmask
52*4882a593Smuzhiyun
53*4882a593SmuzhiyunReturn Value
54*4882a593Smuzhiyun============
55*4882a593Smuzhiyun
56*4882a593SmuzhiyunOn success 0 is returned.
57*4882a593Smuzhiyun
58*4882a593SmuzhiyunOn error -1 is returned, and the ``errno`` variable is set
59*4882a593Smuzhiyunappropriately.
60*4882a593Smuzhiyun
61*4882a593SmuzhiyunGeneric error codes are described at the
62*4882a593Smuzhiyun:ref:`Generic Error Codes <gen-errors>` chapter.
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