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