1.. _usb-error-codes:
  2
  3USB Error codes
  4~~~~~~~~~~~~~~~
  5
  6:Revised: 2004-Oct-21
  7
  8This is the documentation of (hopefully) all possible error codes (and
  9their interpretation) that can be returned from usbcore.
 10
 11Some of them are returned by the Host Controller Drivers (HCDs), which
 12device drivers only see through usbcore.  As a rule, all the HCDs should
 13behave the same except for transfer speed dependent behaviors and the
 14way certain faults are reported.
 15
 16
 17Error codes returned by :c:func:`usb_submit_urb`
 18================================================
 19
 20Non-USB-specific:
 21
 22
 23=============== ===============================================
 240		URB submission went fine
 25
 26``-ENOMEM``	no memory for allocation of internal structures
 27=============== ===============================================
 28
 29USB-specific:
 30
 31=======================	=======================================================
 32``-EBUSY``		The URB is already active.
 33
 34``-ENODEV``		specified USB-device or bus doesn't exist
 35
 36``-ENOENT``		specified interface or endpoint does not exist or
 37			is not enabled
 38
 39``-ENXIO``		host controller driver does not support queuing of
 40			this type of urb.  (treat as a host controller bug.)
 41
 42``-EINVAL``		a) Invalid transfer type specified (or not supported)
 43			b) Invalid or unsupported periodic transfer interval
 44			c) ISO: attempted to change transfer interval
 45			d) ISO: ``number_of_packets`` is < 0
 46			e) various other cases
 47
 48``-EXDEV``		ISO: ``URB_ISO_ASAP`` wasn't specified and all the
 49			frames the URB would be scheduled in have already
 50			expired.
 51
 52``-EFBIG``		Host controller driver can't schedule that many ISO
 53			frames.
 54
 55``-EPIPE``		The pipe type specified in the URB doesn't match the
 56			endpoint's actual type.
 57
 58``-EMSGSIZE``		(a) endpoint maxpacket size is zero; it is not usable
 59			    in the current interface altsetting.
 60			(b) ISO packet is larger than the endpoint maxpacket.
 61			(c) requested data transfer length is invalid: negative
 62			    or too large for the host controller.
 63
 64``-EBADR``		The wLength value in a control URB's setup packet does
 65			not match the URB's transfer_buffer_length.
 66
 67``-ENOSPC``		This request would overcommit the usb bandwidth reserved
 68			for periodic transfers (interrupt, isochronous).
 69
 70``-ESHUTDOWN``		The device or host controller has been disabled due to
 71			some problem that could not be worked around.
 72
 73``-EPERM``		Submission failed because ``urb->reject`` was set.
 74
 75``-EHOSTUNREACH``	URB was rejected because the device is suspended.
 76
 77``-ENOEXEC``		A control URB doesn't contain a Setup packet.
 78=======================	=======================================================
 79
 80Error codes returned by ``in urb->status`` or in ``iso_frame_desc[n].status`` (for ISO)
 81=======================================================================================
 82
 83USB device drivers may only test urb status values in completion handlers.
 84This is because otherwise there would be a race between HCDs updating
 85these values on one CPU, and device drivers testing them on another CPU.
 86
 87A transfer's actual_length may be positive even when an error has been
 88reported.  That's because transfers often involve several packets, so that
 89one or more packets could finish before an error stops further endpoint I/O.
 90
 91For isochronous URBs, the urb status value is non-zero only if the URB is
 92unlinked, the device is removed, the host controller is disabled, or the total
 93transferred length is less than the requested length and the
 94``URB_SHORT_NOT_OK`` flag is set.  Completion handlers for isochronous URBs
 95should only see ``urb->status`` set to zero, ``-ENOENT``, ``-ECONNRESET``,
 96``-ESHUTDOWN``, or ``-EREMOTEIO``. Individual frame descriptor status fields
 97may report more status codes.
 98
 99
100===============================	===============================================
1010				Transfer completed successfully
102
103``-ENOENT``			URB was synchronously unlinked by
104				:c:func:`usb_unlink_urb`
105
106``-EINPROGRESS``		URB still pending, no results yet
107				(That is, if drivers see this it's a bug.)
108
109``-EPROTO`` [#f1]_, [#f2]_	a) bitstuff error
110				b) no response packet received within the
111				   prescribed bus turn-around time
112				c) unknown USB error
113
114``-EILSEQ`` [#f1]_, [#f2]_	a) CRC mismatch
115				b) no response packet received within the
116				   prescribed bus turn-around time
117				c) unknown USB error
118
119				Note that often the controller hardware does
120				not distinguish among cases a), b), and c), so
121				a driver cannot tell whether there was a
122				protocol error, a failure to respond (often
123				caused by device disconnect), or some other
124				fault.
125
126``-ETIME`` [#f2]_		No response packet received within the
127				prescribed bus turn-around time.  This error
128				may instead be reported as
129				``-EPROTO`` or ``-EILSEQ``.
130
131``-ETIMEDOUT``			Synchronous USB message functions use this code
132				to indicate timeout expired before the transfer
133				completed, and no other error was reported
134				by HC.
135
136``-EPIPE`` [#f2]_		Endpoint stalled.  For non-control endpoints,
137				reset this status with
138				:c:func:`usb_clear_halt`.
139
140``-ECOMM``			During an IN transfer, the host controller
141				received data from an endpoint faster than it
142				could be written to system memory
143
144``-ENOSR``			During an OUT transfer, the host controller
145				could not retrieve data from system memory fast
146				enough to keep up with the USB data rate
147
148``-EOVERFLOW`` [#f1]_		The amount of data returned by the endpoint was
149				greater than either the max packet size of the
150				endpoint or the remaining buffer size.
151				"Babble".
152
153``-EREMOTEIO``			The data read from the endpoint did not fill
154				the specified buffer, and ``URB_SHORT_NOT_OK``
155				was set in ``urb->transfer_flags``.
156
157``-ENODEV``			Device was removed.  Often preceded by a burst
158				of other errors, since the hub driver doesn't
159				detect device removal events immediately.
160
161``-EXDEV``			ISO transfer only partially completed
162				(only set in ``iso_frame_desc[n].status``,
163				not ``urb->status``)
164
165``-EINVAL``			ISO madness, if this happens: Log off and
166				go home
167
168``-ECONNRESET``			URB was asynchronously unlinked by
169				:c:func:`usb_unlink_urb`
170
171``-ESHUTDOWN``			The device or host controller has been
172				disabled due to some problem that could not
173				be worked around, such as a physical
174				disconnect.
175===============================	===============================================
176
177
178.. [#f1]
179
180   Error codes like ``-EPROTO``, ``-EILSEQ`` and ``-EOVERFLOW`` normally
181   indicate hardware problems such as bad devices (including firmware)
182   or cables.
183
184.. [#f2]
185
186   This is also one of several codes that different kinds of host
187   controller use to indicate a transfer has failed because of device
188   disconnect.  In the interval before the hub driver starts disconnect
189   processing, devices may receive such fault reports for every request.
190
191
192
193Error codes returned by usbcore-functions
194=========================================
195
196.. note:: expect also other submit and transfer status codes
197
198:c:func:`usb_register`:
199
200======================= ===================================
201``-EINVAL``		error during registering new driver
202======================= ===================================
203
204``usb_get_*/usb_set_*()``,
205:c:func:`usb_control_msg`,
206:c:func:`usb_bulk_msg()`:
207
208======================= ==============================================
209``-ETIMEDOUT``		Timeout expired before the transfer completed.
210======================= ==============================================