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		The pipe type specified in the URB doesn't match the
45		endpoint's actual type.
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-ENOEXEC	A control URB doesn't contain a Setup packet.
64
65
66**************************************************************************
67*                   Error codes returned by in urb->status               *
68*                   or in iso_frame_desc[n].status (for ISO)             *
69**************************************************************************
70
71USB device drivers may only test urb status values in completion handlers.
72This is because otherwise there would be a race between HCDs updating
73these values on one CPU, and device drivers testing them on another CPU.
74
75A transfer's actual_length may be positive even when an error has been
76reported.  That's because transfers often involve several packets, so that
77one or more packets could finish before an error stops further endpoint I/O.
78
79For isochronous URBs, the urb status value is non-zero only if the URB is
80unlinked, the device is removed, the host controller is disabled, or the total
81transferred length is less than the requested length and the URB_SHORT_NOT_OK
82flag is set.  Completion handlers for isochronous URBs should only see
83urb->status set to zero, -ENOENT, -ECONNRESET, -ESHUTDOWN, or -EREMOTEIO.
84Individual frame descriptor status fields may report more status codes.
85
86
870			Transfer completed successfully
88
89-ENOENT			URB was synchronously unlinked by usb_unlink_urb
90
91-EINPROGRESS		URB still pending, no results yet
92			(That is, if drivers see this it's a bug.)
93
94-EPROTO (*, **)		a) bitstuff error
95			b) no response packet received within the
96			   prescribed bus turn-around time
97			c) unknown USB error
98
99-EILSEQ (*, **)		a) CRC mismatch
100			b) no response packet received within the
101			   prescribed bus turn-around time
102			c) unknown USB error
103
104			Note that often the controller hardware does not
105			distinguish among cases a), b), and c), so a
106			driver cannot tell whether there was a protocol
107			error, a failure to respond (often caused by
108			device disconnect), or some other fault.
109
110-ETIME (**)		No response packet received within the prescribed
111			bus turn-around time.  This error may instead be
112			reported as -EPROTO or -EILSEQ.
113
114-ETIMEDOUT		Synchronous USB message functions use this code
115			to indicate timeout expired before the transfer
116			completed, and no other error was reported by HC.
117
118-EPIPE (**)		Endpoint stalled.  For non-control endpoints,
119			reset this status with usb_clear_halt().
120
121-ECOMM			During an IN transfer, the host controller
122			received data from an endpoint faster than it
123			could be written to system memory
124
125-ENOSR			During an OUT transfer, the host controller
126			could not retrieve data from system memory fast
127			enough to keep up with the USB data rate
128
129-EOVERFLOW (*)		The amount of data returned by the endpoint was
130			greater than either the max packet size of the
131			endpoint or the remaining buffer size.  "Babble".
132
133-EREMOTEIO		The data read from the endpoint did not fill the
134			specified buffer, and URB_SHORT_NOT_OK was set in
135			urb->transfer_flags.
136
137-ENODEV			Device was removed.  Often preceded by a burst of
138			other errors, since the hub driver doesn't detect
139			device removal events immediately.
140
141-EXDEV			ISO transfer only partially completed
142			(only set in iso_frame_desc[n].status, not urb->status)
143
144-EINVAL			ISO madness, if this happens: Log off and go home
145
146-ECONNRESET		URB was asynchronously unlinked by usb_unlink_urb
147
148-ESHUTDOWN		The device or host controller has been disabled due
149			to some problem that could not be worked around,
150			such as a physical disconnect.
151
152
153(*) Error codes like -EPROTO, -EILSEQ and -EOVERFLOW normally indicate
154hardware problems such as bad devices (including firmware) or cables.
155
156(**) This is also one of several codes that different kinds of host
157controller use to indicate a transfer has failed because of device
158disconnect.  In the interval before the hub driver starts disconnect
159processing, devices may receive such fault reports for every request.
160
161
162
163**************************************************************************
164*              Error codes returned by usbcore-functions                 *
165*           (expect also other submit and transfer status codes)         *
166**************************************************************************
167
168usb_register():
169-EINVAL			error during registering new driver
170
171usb_get_*/usb_set_*():
172usb_control_msg():
173usb_bulk_msg():
174-ETIMEDOUT		Timeout expired before the transfer completed.
175