1.. -*- coding: utf-8; mode: rst -*- 2 3.. _gen_errors: 4 5******************* 6Generic 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. 106