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