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