[linux.git] / Documentation / usb / error-codes.txt

Revised: 2004-Oct-21

This is the documentation of (hopefully) all possible error codes (and
their interpretation) that can be returned from usbcore.

Some of them are returned by the Host Controller Drivers (HCDs), which
device drivers only see through usbcore.  As a rule, all the HCDs should
behave the same except for transfer speed dependent behaviors and the
way certain faults are reported.


**************************************************************************
*                   Error codes returned by usb_submit_urb               *
**************************************************************************

Non-USB-specific:

0		URB submission went fine

-ENOMEM		no memory for allocation of internal structures	

USB-specific:

-ENODEV		specified USB-device or bus doesn't exist

-ENOENT		specified interface or endpoint does not exist or
		is not enabled

-ENXIO		host controller driver does not support queuing of this type
		of urb.  (treat as a host controller bug.)

-EINVAL		a) Invalid transfer type specified (or not supported)
		b) Invalid or unsupported periodic transfer interval
		c) ISO: attempted to change transfer interval
		d) ISO: number_of_packets is < 0
		e) various other cases

-EAGAIN		a) specified ISO start frame too early
		b) (using ISO-ASAP) too much scheduled for the future
		   wait some time and try again.

-EFBIG		Host controller driver can't schedule that many ISO frames.

-EPIPE		The pipe type specified in the URB doesn't match the
		endpoint's actual type.

-EMSGSIZE	(a) endpoint maxpacket size is zero; it is not usable
		    in the current interface altsetting.
		(b) ISO packet is larger than the endpoint maxpacket.
		(c) requested data transfer length is invalid: negative
		    or too large for the host controller.

-ENOSPC		This request would overcommit the usb bandwidth reserved
		for periodic transfers (interrupt, isochronous).

-ESHUTDOWN	The device or host controller has been disabled due to some
		problem that could not be worked around.

-EPERM		Submission failed because urb->reject was set.

-EHOSTUNREACH	URB was rejected because the device is suspended.

-ENOEXEC	A control URB doesn't contain a Setup packet.


**************************************************************************
*                   Error codes returned by in urb->status               *
*                   or in iso_frame_desc[n].status (for ISO)             *
**************************************************************************

USB device drivers may only test urb status values in completion handlers.
This is because otherwise there would be a race between HCDs updating
these values on one CPU, and device drivers testing them on another CPU.

A transfer's actual_length may be positive even when an error has been
reported.  That's because transfers often involve several packets, so that
one or more packets could finish before an error stops further endpoint I/O.

For isochronous URBs, the urb status value is non-zero only if the URB is
unlinked, the device is removed, the host controller is disabled, or the total
transferred length is less than the requested length and the URB_SHORT_NOT_OK
flag is set.  Completion handlers for isochronous URBs should only see
urb->status set to zero, -ENOENT, -ECONNRESET, -ESHUTDOWN, or -EREMOTEIO.
Individual frame descriptor status fields may report more status codes.


0			Transfer completed successfully

-ENOENT			URB was synchronously unlinked by usb_unlink_urb

-EINPROGRESS		URB still pending, no results yet
			(That is, if drivers see this it's a bug.)

-EPROTO (*, **)		a) bitstuff error
			b) no response packet received within the
			   prescribed bus turn-around time
			c) unknown USB error 

-EILSEQ (*, **)		a) CRC mismatch
			b) no response packet received within the
			   prescribed bus turn-around time
			c) unknown USB error 

			Note that often the controller hardware does not
			distinguish among cases a), b), and c), so a
			driver cannot tell whether there was a protocol
			error, a failure to respond (often caused by
			device disconnect), or some other fault.

-ETIME (**)		No response packet received within the prescribed
			bus turn-around time.  This error may instead be
			reported as -EPROTO or -EILSEQ.

-ETIMEDOUT		Synchronous USB message functions use this code
			to indicate timeout expired before the transfer
			completed, and no other error was reported by HC.

-EPIPE (**)		Endpoint stalled.  For non-control endpoints,
			reset this status with usb_clear_halt().

-ECOMM			During an IN transfer, the host controller
			received data from an endpoint faster than it
			could be written to system memory

-ENOSR			During an OUT transfer, the host controller
			could not retrieve data from system memory fast
			enough to keep up with the USB data rate

-EOVERFLOW (*)		The amount of data returned by the endpoint was
			greater than either the max packet size of the
			endpoint or the remaining buffer size.  "Babble".

-EREMOTEIO		The data read from the endpoint did not fill the
			specified buffer, and URB_SHORT_NOT_OK was set in
			urb->transfer_flags.

-ENODEV			Device was removed.  Often preceded by a burst of
			other errors, since the hub driver doesn't detect
			device removal events immediately.

-EXDEV			ISO transfer only partially completed
			(only set in iso_frame_desc[n].status, not urb->status)

-EINVAL			ISO madness, if this happens: Log off and go home

-ECONNRESET		URB was asynchronously unlinked by usb_unlink_urb

-ESHUTDOWN		The device or host controller has been disabled due
			to some problem that could not be worked around,
			such as a physical disconnect.


(*) Error codes like -EPROTO, -EILSEQ and -EOVERFLOW normally indicate
hardware problems such as bad devices (including firmware) or cables.

(**) This is also one of several codes that different kinds of host
controller use to indicate a transfer has failed because of device
disconnect.  In the interval before the hub driver starts disconnect
processing, devices may receive such fault reports for every request.


**************************************************************************
*              Error codes returned by usbcore-functions                 *
*           (expect also other submit and transfer status codes)         *
**************************************************************************

usb_register():
-EINVAL			error during registering new driver

usb_get_*/usb_set_*():
usb_control_msg():
usb_bulk_msg():
-ETIMEDOUT		Timeout expired before the transfer completed.
Commit	Line	Data
1da177e4 LT	1	Revised: 2004-Oct-21
	2
	3	This is the documentation of (hopefully) all possible error codes (and
	4	their interpretation) that can be returned from usbcore.
	5
	6	Some of them are returned by the Host Controller Drivers (HCDs), which
	7	device drivers only see through usbcore. As a rule, all the HCDs should
	8	behave the same except for transfer speed dependent behaviors and the
	9	way certain faults are reported.
	10
	11
	12	**************************************************************************
	13	* Error codes returned by usb_submit_urb *
	14	**************************************************************************
	15
	16	Non-USB-specific:
	17
	18	0 URB submission went fine
	19
	20	-ENOMEM no memory for allocation of internal structures
	21
	22	USB-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
f661c6f8 AS	44	-EPIPE The pipe type specified in the URB doesn't match the
f661c6f8 AS	45	endpoint's actual type.
1da177e4 LT	46
	47	-EMSGSIZE (a) endpoint maxpacket size is zero; it is not usable
	48	in the current interface altsetting.
620948a0 AS	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.
1da177e4 LT	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
f661c6f8 AS	63	-ENOEXEC A control URB doesn't contain a Setup packet.
f661c6f8 AS	64
1da177e4 LT	65
	66	**************************************************************************
	67	* Error codes returned by in urb->status *
	68	* or in iso_frame_desc[n].status (for ISO) *
	69	**************************************************************************
	70
	71	USB device drivers may only test urb status values in completion handlers.
	72	This is because otherwise there would be a race between HCDs updating
	73	these values on one CPU, and device drivers testing them on another CPU.
	74
	75	A transfer's actual_length may be positive even when an error has been
	76	reported. That's because transfers often involve several packets, so that
	77	one or more packets could finish before an error stops further endpoint I/O.
	78
a9e75863 SS	79	For isochronous URBs, the urb status value is non-zero only if the URB is
	80	unlinked, the device is removed, the host controller is disabled, or the total
	81	transferred length is less than the requested length and the URB_SHORT_NOT_OK
	82	flag is set. Completion handlers for isochronous URBs should only see
	83	urb->status set to zero, -ENOENT, -ECONNRESET, -ESHUTDOWN, or -EREMOTEIO.
	84	Individual frame descriptor status fields may report more status codes.
	85
1da177e4 LT	86
	87	0 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
38e2bfc9	110	-ETIME (**) No response packet received within the prescribed
1da177e4 LT	111	bus turn-around time. This error may instead be
	112	reported as -EPROTO or -EILSEQ.
	113
38e2bfc9 PZ	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.
1da177e4 LT	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
fff9289b	138	other errors, since the hub driver doesn't detect
1da177e4 LT	139	device removal events immediately.
	140
	141	-EXDEV ISO transfer only partially completed
a9e75863	142	(only set in iso_frame_desc[n].status, not urb->status)
1da177e4 LT	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
	154	hardware problems such as bad devices (including firmware) or cables.
	155
	156	(**) This is also one of several codes that different kinds of host
670e9f34	157	controller use to indicate a transfer has failed because of device
1da177e4 LT	158	disconnect. In the interval before the hub driver starts disconnect
	159	processing, 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
	168	usb_register():
	169	-EINVAL error during registering new driver
	170
	171	usb_get_/usb_set_():
	172	usb_control_msg():
	173	usb_bulk_msg():
	174	-ETIMEDOUT Timeout expired before the transfer completed.