.. _usb-error-codes: USB Error codes~~~~~~~~~~~~~~~ :Revised: 2004-Oct-21 This is the documentation of (hopefully) all possible error codes (andtheir interpretation) that can be returned from usbcore. Some of them are returned by the Host Controller Drivers (HCDs), whichdevice drivers only see through usbcore.  As a rule, all the HCDs shouldbehave the same except for transfer speed dependent behaviors and theway certain faults are reported.  Error codes returned by :c:func:`usb_submit_urb`================================================ Non-USB-specific:  =============== ===============================================0		URB submission went fine ``-ENOMEM``	no memory for allocation of internal structures=============== =============================================== USB-specific: =======================	=======================================================``-EBUSY``		The URB is already active. ``-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 ``-EXDEV``		ISO: ``URB_ISO_ASAP`` wasn't specified and all the			frames the URB would be scheduled in have already			expired. ``-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. ``-EBADR``		The wLength value in a control URB's setup packet does			not match the URB's transfer_buffer_length. ``-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 updatingthese 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 beenreported.  That's because transfers often involve several packets, so thatone 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 isunlinked, the device is removed, the host controller is disabled, or the totaltransferred length is less than the requested length and the``URB_SHORT_NOT_OK`` flag is set.  Completion handlers for isochronous URBsshould only see ``urb->status`` set to zero, ``-ENOENT``, ``-ECONNRESET``,``-ESHUTDOWN``, or ``-EREMOTEIO``. Individual frame descriptor status fieldsmay report more status codes.  ===============================	===============================================0				Transfer completed successfully ``-ENOENT``			URB was synchronously unlinked by				:c:func:`usb_unlink_urb` ``-EINPROGRESS``		URB still pending, no results yet				(That is, if drivers see this it's a bug.) ``-EPROTO`` [#f1]_, [#f2]_	a) bitstuff error				b) no response packet received within the				   prescribed bus turn-around time				c) unknown USB error ``-EILSEQ`` [#f1]_, [#f2]_	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`` [#f2]_		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`` [#f2]_		Endpoint stalled.  For non-control endpoints,				reset this status with				:c:func:`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`` [#f1]_		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				:c:func:`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.===============================	===============================================  .. [#f1]    Error codes like ``-EPROTO``, ``-EILSEQ`` and ``-EOVERFLOW`` normally   indicate hardware problems such as bad devices (including firmware)   or cables. .. [#f2]    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========================================= .. note:: expect also other submit and transfer status codes :c:func:`usb_register`: ======================= ===================================``-EINVAL``		error during registering new driver======================= =================================== ``usb_get_*/usb_set_*()``,:c:func:`usb_control_msg`,:c:func:`usb_bulk_msg()`: ======================= ==============================================``-ETIMEDOUT``		Timeout expired before the transfer completed.======================= ==============================================