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1 .. -*- coding: utf-8; mode: rst -*-
2
3 .. _gen_errors:
4
5 *******************
6 Generic Error Codes
7 *******************
8
9
10 .. _gen-errors:
11
12 .. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
13
14 .. flat-table:: Generic error codes
15 :header-rows: 0
16 :stub-columns: 0
17 :widths: 1 16
18
19
20 - .. row 1
21
22 - ``EAGAIN`` (aka ``EWOULDBLOCK``)
23
24 - The ioctl can't be handled because the device is in state where it
25 can't perform it. This could happen for example in case where
26 device is sleeping and ioctl is performed to query statistics. It
27 is also returned when the ioctl would need to wait for an event,
28 but the device was opened in non-blocking mode.
29
30 - .. row 2
31
32 - ``EBADF``
33
34 - The file descriptor is not a valid.
35
36 - .. row 3
37
38 - ``EBUSY``
39
40 - The ioctl can't be handled because the device is busy. This is
41 typically return while device is streaming, and an ioctl tried to
42 change something that would affect the stream, or would require
43 the usage of a hardware resource that was already allocated. The
44 ioctl must not be retried without performing another action to fix
45 the problem first (typically: stop the stream before retrying).
46
47 - .. row 4
48
49 - ``EFAULT``
50
51 - There was a failure while copying data from/to userspace, probably
52 caused by an invalid pointer reference.
53
54 - .. row 5
55
56 - ``EINVAL``
57
58 - One or more of the ioctl parameters are invalid or out of the
59 allowed range. This is a widely used error code. See the
60 individual ioctl requests for specific causes.
61
62 - .. row 6
63
64 - ``ENODEV``
65
66 - Device not found or was removed.
67
68 - .. row 7
69
70 - ``ENOMEM``
71
72 - There's not enough memory to handle the desired operation.
73
74 - .. row 8
75
76 - ``ENOTTY``
77
78 - The ioctl is not supported by the driver, actually meaning that
79 the required functionality is not available, or the file
80 descriptor is not for a media device.
81
82 - .. row 9
83
84 - ``ENOSPC``
85
86 - On USB devices, the stream ioctl's can return this error, meaning
87 that this request would overcommit the usb bandwidth reserved for
88 periodic transfers (up to 80% of the USB bandwidth).
89
90 - .. row 10
91
92 - ``EPERM``
93
94 - Permission denied. Can be returned if the device needs write
95 permission, or some special capabilities is needed (e. g. root)
96
97 .. note::
98
99 #. This list is not exaustive; ioctls may return other error codes.
100 Since errors may have side effects such as a driver reset,
101 applications should abort on unexpected errors, or otherwise
102 assume that the device is in a bad state.
103
104 #. Request-specific error codes are listed in the individual
105 requests descriptions.