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 Specified endpoint is stalled. For non-control endpoints, 45 reset this status with usb_clear_halt(). 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 64************************************************************************** 65* Error codes returned by in urb->status * 66* or in iso_frame_desc[n].status (for ISO) * 67************************************************************************** 68 69USB device drivers may only test urb status values in completion handlers. 70This is because otherwise there would be a race between HCDs updating 71these values on one CPU, and device drivers testing them on another CPU. 72 73A transfer's actual_length may be positive even when an error has been 74reported. That's because transfers often involve several packets, so that 75one or more packets could finish before an error stops further endpoint I/O. 76 77 780 Transfer completed successfully 79 80-ENOENT URB was synchronously unlinked by usb_unlink_urb 81 82-EINPROGRESS URB still pending, no results yet 83 (That is, if drivers see this it's a bug.) 84 85-EPROTO (*, **) a) bitstuff error 86 b) no response packet received within the 87 prescribed bus turn-around time 88 c) unknown USB error 89 90-EILSEQ (*, **) a) CRC mismatch 91 b) no response packet received within the 92 prescribed bus turn-around time 93 c) unknown USB error 94 95 Note that often the controller hardware does not 96 distinguish among cases a), b), and c), so a 97 driver cannot tell whether there was a protocol 98 error, a failure to respond (often caused by 99 device disconnect), or some other fault. 100 101-ETIME (**) No response packet received within the prescribed 102 bus turn-around time. This error may instead be 103 reported as -EPROTO or -EILSEQ. 104 105-ETIMEDOUT Synchronous USB message functions use this code 106 to indicate timeout expired before the transfer 107 completed, and no other error was reported by HC. 108 109-EPIPE (**) Endpoint stalled. For non-control endpoints, 110 reset this status with usb_clear_halt(). 111 112-ECOMM During an IN transfer, the host controller 113 received data from an endpoint faster than it 114 could be written to system memory 115 116-ENOSR During an OUT transfer, the host controller 117 could not retrieve data from system memory fast 118 enough to keep up with the USB data rate 119 120-EOVERFLOW (*) The amount of data returned by the endpoint was 121 greater than either the max packet size of the 122 endpoint or the remaining buffer size. "Babble". 123 124-EREMOTEIO The data read from the endpoint did not fill the 125 specified buffer, and URB_SHORT_NOT_OK was set in 126 urb->transfer_flags. 127 128-ENODEV Device was removed. Often preceded by a burst of 129 other errors, since the hub driver doesn't detect 130 device removal events immediately. 131 132-EXDEV ISO transfer only partially completed 133 look at individual frame status for details 134 135-EINVAL ISO madness, if this happens: Log off and go home 136 137-ECONNRESET URB was asynchronously unlinked by usb_unlink_urb 138 139-ESHUTDOWN The device or host controller has been disabled due 140 to some problem that could not be worked around, 141 such as a physical disconnect. 142 143 144(*) Error codes like -EPROTO, -EILSEQ and -EOVERFLOW normally indicate 145hardware problems such as bad devices (including firmware) or cables. 146 147(**) This is also one of several codes that different kinds of host 148controller use to indicate a transfer has failed because of device 149disconnect. In the interval before the hub driver starts disconnect 150processing, devices may receive such fault reports for every request. 151 152 153 154************************************************************************** 155* Error codes returned by usbcore-functions * 156* (expect also other submit and transfer status codes) * 157************************************************************************** 158 159usb_register(): 160-EINVAL error during registering new driver 161 162usb_get_*/usb_set_*(): 163usb_control_msg(): 164usb_bulk_msg(): 165-ETIMEDOUT Timeout expired before the transfer completed. 166