-Revised: 2002-Feb-09.
+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.
+behave the same except for transfer speed dependent behaviors and the
+way certain faults are reported.
**************************************************************************
of urb. (treat as a host controller bug.)
-EINVAL a) Invalid transfer type specified (or not supported)
- b) Invalid interrupt interval (0<=n<256)
- c) more than one interrupt packet requested
+ 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 too much ISO frames requested (currently uhci>900)
+-EFBIG Host controller driver can't schedule that many ISO frames.
-EPIPE Specified endpoint is stalled. For non-control endpoints,
reset this status with usb_clear_halt().
--EMSGSIZE endpoint message size is zero, do interface/alternate setting
+-EMSGSIZE (a) endpoint maxpacket size is zero; it is not usable
+ in the current interface altsetting.
+ (b) ISO packet is biger than endpoint maxpacket
+ (c) requested data transfer size is invalid (negative)
--ENOSPC The host controller's bandwidth is already consumed and
- this request would push it past its allowed limit.
+-ENOSPC This request would overcommit the usb bandwidth reserved
+ for periodic transfers (interrupt, isochronous).
--ESHUTDOWN The host controller has been disabled due to some
+-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.
+
**************************************************************************
* Error codes returned by in urb->status *
-EINPROGRESS URB still pending, no results yet
(That is, if drivers see this it's a bug.)
--EPROTO (*) a) bitstuff error
+-EPROTO (*, **) a) bitstuff error
b) no response packet received within the
prescribed bus turn-around time
c) unknown USB error
--EILSEQ (*) CRC mismatch
+-EILSEQ (*, **) a) CRC mismatch
+ b) no response packet received within the
+ prescribed bus turn-around time
+ c) unknown USB error
--EPIPE Endpoint stalled. For non-control endpoints,
+ In cases b) and c) either -EPROTO or -EILSEQ
+ may be returned. 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.
+
+-EPIPE (**) Endpoint stalled. For non-control endpoints,
reset this status with usb_clear_halt().
-ECOMM During an IN transfer, the host controller
specified buffer, and URB_SHORT_NOT_OK was set in
urb->transfer_flags.
--ETIMEDOUT transfer timed out, NAK
-
-ENODEV Device was removed. Often preceded by a burst of
other errors, since the hub driver does't detect
device removal events immediately.
-ECONNRESET URB was asynchronously unlinked by usb_unlink_urb
--ESHUTDOWN The host controller has been disabled due to some
- problem that could not be worked around.
+-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 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.
+
**************************************************************************
usb_get_*/usb_set_*():
usb_control_msg():
usb_bulk_msg():
- All USB errors (submit/status) can occur
+-ETIMEDOUT timeout expired before the transfer completed
git://git.onelab.eu / linux-2.6.git / blobdiff