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- .. -*- coding: utf-8; mode: rst -*-
- .. _gen_errors:
- *******************
- Generic Error Codes
- *******************
- .. _gen-errors:
- .. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
- .. flat-table:: Generic error codes
- :header-rows: 0
- :stub-columns: 0
- :widths: 1 16
- - .. row 1
- - ``EAGAIN`` (aka ``EWOULDBLOCK``)
- - The ioctl can't be handled because the device is in state where it
- can't perform it. This could happen for example in case where
- device is sleeping and ioctl is performed to query statistics. It
- is also returned when the ioctl would need to wait for an event,
- but the device was opened in non-blocking mode.
- - .. row 2
- - ``EBADF``
- - The file descriptor is not a valid.
- - .. row 3
- - ``EBUSY``
- - The ioctl can't be handled because the device is busy. This is
- typically return while device is streaming, and an ioctl tried to
- change something that would affect the stream, or would require
- the usage of a hardware resource that was already allocated. The
- ioctl must not be retried without performing another action to fix
- the problem first (typically: stop the stream before retrying).
- - .. row 4
- - ``EFAULT``
- - There was a failure while copying data from/to userspace, probably
- caused by an invalid pointer reference.
- - .. row 5
- - ``EINVAL``
- - One or more of the ioctl parameters are invalid or out of the
- allowed range. This is a widely used error code. See the
- individual ioctl requests for specific causes.
- - .. row 6
- - ``ENODEV``
- - Device not found or was removed.
- - .. row 7
- - ``ENOMEM``
- - There's not enough memory to handle the desired operation.
- - .. row 8
- - ``ENOTTY``
- - The ioctl is not supported by the driver, actually meaning that
- the required functionality is not available, or the file
- descriptor is not for a media device.
- - .. row 9
- - ``ENOSPC``
- - On USB devices, the stream ioctl's can return this error, meaning
- that this request would overcommit the usb bandwidth reserved for
- periodic transfers (up to 80% of the USB bandwidth).
- - .. row 10
- - ``EPERM``
- - Permission denied. Can be returned if the device needs write
- permission, or some special capabilities is needed (e. g. root)
- .. note::
- #. This list is not exaustive; ioctls may return other error codes.
- Since errors may have side effects such as a driver reset,
- applications should abort on unexpected errors, or otherwise
- assume that the device is in a bad state.
- #. Request-specific error codes are listed in the individual
- requests descriptions.
|
