Hi Sarah, On Fri, Jul 19, 2013 at 12:09 AM, Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx> wrote: > On Thu, Jul 18, 2013 at 04:28:01PM -0400, Peter Hurley wrote: >> [ +cc Sarah Sharp, linux-usb ] >> >> On 07/18/2013 09:21 AM, Nestor Lopez Casado wrote: >> >This reverts commit 8af6c08830b1ae114d1a8b548b1f8b056e068887. >> > >> >This patch re-adds the workaround introduced by 596264082f10dd4 >> >which was reverted by 8af6c08830b1ae114. >> > >> >The original patch 596264 was needed to overcome a situation where >> >the hid-core would drop incoming reports while probe() was being >> >executed. >> > >> >This issue was solved by c849a6143bec520af which added >> >hid_device_io_start() and hid_device_io_stop() that enable a specific >> >hid driver to opt-in for input reports while its probe() is being >> >executed. >> > >> >Commit a9dd22b730857347 modified hid-logitech-dj so as to use the >> >functionality added to hid-core. Having done that, workaround 596264 >> >was no longer necessary and was reverted by 8af6c08. >> > >> >We now encounter a different problem that ends up 'again' thwarting >> >the Unifying receiver enumeration. The problem is time and usb controller >> >dependent. Ocasionally the reports sent to the usb receiver to start >> >the paired devices enumeration fail with -EPIPE and the receiver never >> >gets to enumerate the paired devices. >> > >> >With dcd9006b1b053c7b1c the problem was "hidden" as the call to the usb >> >driver became asynchronous and none was catching the error from the >> >failing URB. >> > >> >As the root cause for this failing SET_REPORT is not understood yet, >> >-possibly a race on the usb controller drivers or a problem with the >> >Unifying receiver- reintroducing this workaround solves the problem. >> >> >> Before we revert to using the workaround, I'd like to suggest that >> this new "hidden" problem may be an interaction with the xhci_hcd host >> controller driver only. >> >> Looking at the related bug, the OP indicates the machine only has >> USB3 ports. Additionally, comments #7, #100, and #104 of the original >> bug report [1] add additional information that would seem to confirm >> this suspicion. > > Question: does this USB device need a control transfer to reset its > endpoints when the endpoints are not actually halted? If so, yes, that > is a known xHCI driver bug that needs to be fixed. The xHCI host will > not accept a Reset Endpoint command when the endpoints are not actually > halted, but the USB core will send the control transfer to reset the > endpoint. That means the device and host toggles will be out of sync, > and all messages will start to fail with -EPIPE. Could you re-phrase your question providing a bit more detail? I don't quite get the idea. > > Can the OP capture a usbmon trace when the device starts failing? That > will reveal whether this actually is the issue. dmesg output with > CONFIG_USB_DEBUG and CONFIG_USB_XHCI_HCD_DEBUGGING turned on would also > be helpful. > > Sarah Sharp Cheers, Nestor -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
