From: Peter Wu <lekensteyn@gmail.com>
To: Peter Hurley <peter@hurleysoftware.com>
Cc: Nestor Lopez Casado <nlopezcasad@logitech.com>, jkosina@suse.cz,
        benjamin.tissoires@gmail.com, adlr@chromium.org,
        joseph.salisbury@canonical.com, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Sarah Sharp <sarah.a.sharp@linux.intel.com>, linux-usb@vger.kernel.org
Subject: Re: [PATCH 1/2] Revert "Revert "HID: Fix logitech-dj: missing Unifying device issue""
Date: Tue, 13 Aug 2013 17:42:32 +0200
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On Tuesday 13 August 2013 08:13:17 Peter Hurley wrote:
> On 08/12/2013 05:54 PM, Peter Wu wrote:
> > On Thursday 18 July 2013 16:28:01 Peter Hurley wrote:
> >> 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 add additional information that would seem to confirm
> >> this suspicion.
> >> 
> >> Let me add I have this USB device running on the uhci_hcd driver
> >> with or without this workaround on v3.10.
> > 
> > This problem does not seem specific to xhci, uhci seems also effected.
> 
> If true, it would certainly help to have a bug report confirming uhci
> failure from a bare-metal system which contained:
> 1) kernel version
> 2) complete dmesg output
> 3) lsusb -v output
> 4) lsmod output
> 5) usbmon capture from a plug attempt

I was too fast in drawing a conclusion, besides the kernel I also upgraded 
some other packages. Today the issue also showed up in 3.9.9 + updated 
packages.

When checking the dmesg, the issue solved by this patch did not occur (the 
enumeration was successful).

> > Today I
> > upgraded a system (running Arch Linux) from kernel 3.9.9 to 3.10.5. After
> > a
> > reboot to 3.10.5, things broke. The setup:
> > 
> > - There are two USB receivers plugged into USB 1.1 ports (different buses
> > according to lsusb, uhci), each receiver is paired to a K360 keyboard.
> > - One of the receivers are passed to a QEMU guest with -usbdevice
> > host:$busid. $devid. This keyboard is working (probably because QEMU
> > performed a reset). - Since 3.10.5, the keyboard that is *not* passed to
> > the QEMU guest is not functioning on reboot.
> > 
> > After closing the QEMU guest, the USB bus gets reset(?) after which the
> > other keyboard suddenly gets detected. I had only booted 3.10.5 twice
> > before rolling back to 3.9.9, both boots triggered the issue. Do I need
> > to provide a usbmon, lsusb, dmesg and/ or other details from 3.10.5?
> 
> Do both keyboards work on bare metal? Seems like this problem might be
> specific to qemu (or kvm) and you may get more insight on those lists.

I haven't tested that, the system automatically boots into openbox + QEMU. 
Previously, both keyboards worked on bare metal, so I think it still works.

> > Note that there are other Arch Linux users who have reported issues[1][2]
> 
> Unfortunately, not even one user in the referenced reports identified
> the usb hub the receiver was plugged into.

I've asked it now.

> > since upgrading to 3.10.z. Triggering a re-enumeration by writing the
> > magic
> > HID++ message[3] makes the paired devices appear again (as reported in
> > forums[1], I haven't tried this on the affected UHCI machine).
> > 
> > While the underlying bug is fixed, can this patch be forwarded to stable?
> > I see that 3.10.6 has been released, but still without this patch.
> 
> This is still a workaround and not really a fix for the underlying bug.

I meant to say, "while the underlying bug is *being* fixed". Anyway, can this 
patch be applied to 3.10?

Sorry for the confusion with uhci, looking further it seems that the wrong USB 
receiver is being passed to QEMU. It's not a kernel issue, perhaps I can blame 
libusbx.

Regards,
Peter
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