Documentation/media/uapi/gen-errors.rst

   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
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  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     -  .. row 11
  98
  99        -  ``EIO``
 100
 101        -  I/O error. Typically used when there are problems communicating with
 102           a hardware device. This could indicate broken or flaky hardware.
 103           It's a 'Something is wrong, I give up!' type of error.
 104
 105 .. note::
 106
 107   #. This list is not exhaustive; ioctls may return other error codes.
 108      Since errors may have side effects such as a driver reset,
 109      applications should abort on unexpected errors, or otherwise
 110      assume that the device is in a bad state.
 111
 112   #. Request-specific error codes are listed in the individual
 113      requests descriptions.