42969726a1
The existing uAPI documentation does not adequately describe how the kernel handles the case where the underlying hardware or driver does not support the requested configuration. Add a Configuration Support section describing that behaviour to both the v1 and v2 documentation, and better document the errors returned where the requested configuration cannot be supported. Signed-off-by: Kent Gibson <warthog618@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
80 lines
2.3 KiB
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80 lines
2.3 KiB
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.. SPDX-License-Identifier: GPL-2.0
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.. _gpio_errors:
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*******************
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GPIO Error Codes
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*******************
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.. _gpio-errors:
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.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
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.. flat-table:: Common GPIO error codes
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 16
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- - ``EAGAIN`` (aka ``EWOULDBLOCK``)
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- The device was opened in non-blocking mode and a read can't
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be performed as there is no data available.
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- - ``EBADF``
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- The file descriptor is not valid.
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- - ``EBUSY``
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- The ioctl can't be handled because the device is busy. Typically
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returned when an ioctl attempts something that would require the
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usage of a resource that was already allocated. The ioctl must not
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be retried without performing another action to fix the problem
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first.
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- - ``EFAULT``
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- There was a failure while copying data from/to userspace, probably
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caused by an invalid pointer reference.
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- - ``EINVAL``
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- One or more of the ioctl parameters are invalid or out of the
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allowed range. This is a widely used error code.
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- - ``ENODEV``
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- Device not found or was removed.
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- - ``ENOMEM``
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- There's not enough memory to handle the desired operation.
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- - ``EPERM``
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- Permission denied. Typically returned in response to an attempt
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to perform an action incompatible with the current line
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configuration.
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- - ``EIO``
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- I/O error. Typically returned when there are problems communicating
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with a hardware device or requesting features that hardware does not
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support. This could indicate broken or flaky hardware.
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It's a 'Something is wrong, I give up!' type of error.
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- - ``ENXIO``
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- Typically returned when a feature requiring interrupt support was
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requested, but the line does not support interrupts.
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.. note::
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#. This list is not exhaustive; ioctls may return other error codes.
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Since errors may have side effects such as a driver reset,
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applications should abort on unexpected errors, or otherwise
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assume that the device is in a bad state.
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#. Request-specific error codes are listed in the individual
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requests descriptions.
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