Messages in this thread | | | Date | Thu, 18 Jul 2013 19:37:03 -0400 | From | Peter Hurley <> | Subject | Re: [PATCH 1/2] Revert "Revert "HID: Fix logitech-dj: missing Unifying device issue"" |
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On 07/18/2013 06:09 PM, Sarah Sharp 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. > > 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,
I forwarded your usbmon capture request to the OP in the bug report (I don't have an email address for the reporter).
As far as getting printk output from a custom kernel, I think that may be beyond the reporter's capability. Perhaps one of the Ubuntu devs triaging this bug could provide a test kernel for the OP with those options on.
Joseph, would you be willing to do that?
Regards, Peter Hurley
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