If an error occurs during execution of a USB request, the USBA framework calls a client driver's exception callback handler to relay what happened. The
host controller reports transport errors to the exception callback handler through the handler's request argument's completion reason (usb_cr_t) field. A completion reason of USB_CR_OK means the transfer completed with no errors detected.
The usb_cr_t enumerated type contains the following definitions:
USB_CR_OK
The transfer completed without any errors being detected.
USB_CR_CRC
CRC error was detected.
USB_CR_BITSTUFFING
Bit stuffing violation was detected.
USB_CR_DATA_TOGGLE_MM
Data toggle packet identifier did not match expected value.
USB_CR_STALL
The device endpoint indicated that it is stalled. If autoclearing is enabled for the request (request attributes has USB_ATTRS_AUTOCLEARING set), check the callback flags (usb_cb_flags_t) in the callback handler to determine whether the stall is a
functional stall (USB_CB_FUNCTIONAL_STALL) or a protocol stall (USB_CB_PROTOCOL_STALL). Please see usb_request_attributes(9S) for more information on autoclearing.
USB_CR_DEV_NOT_RESP
Host controller timed out while waiting for device to respond.
USB_CR_PID_CHECKFAILURE
Check bits on the packet identifier returned from the device were not as expected.
USB_CR_UNEXP_PID
Packet identifier received was not valid.
USB_CR_DATA_OVERRUN
Amount of data returned exceeded either the maximum packet size of the endpoint or the remaining buffer size.
USB_CR_DATA_UNDERRUN
Amount of data returned was not sufficient to fill the specified buffer and the USB_ATTRS_SHORT_XFER_OK attribute was not set. Please see usb_request_attributes(9S) for more information on allowance of short transfers.
USB_CR_BUFFER_OVERRUN
A device sent data faster than the system could digest it.
USB_CR_BUFFER_UNDERRUN
The host controller could not get data from the system fast enough to keep up with the required USB data rate.
USB_CR_TIMEOUT
A timeout specified in a control, bulk, or one-time interrupt request has expired.
USB_CR_NOT_ACCESSED
Request was not accessed nor processed by the host controller.
USB_CR_NO_RESOURCES
No resources were available to continue servicing a periodic interrupt or isochronous request.
USB_CR_STOPPED_POLLING
Servicing of the current periodic request cannot continue because polling on an interrupt-IN or isochronous-IN endpoint has stopped.
USB_CR_PIPE_CLOSING
Request was not started because the pipe to which it was queued was closing or closed.
USB_CR_PIPE_RESET
Request was not started because the pipe to which it was queued was reset.
USB_CR_NOT_SUPPORTED
Request or command is not supported.
USB_CR_FLUSHED
Request was not completed because the pipe to which it was queued went to an error state, became stalled, was reset or was closed.
USB_CR_HC_HARDWARE_ERR
Request could not be completed due to a general host controller hardware error.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
