Comment # 11 on bug 942211 from Jan Ritzerfeld

(In reply to Takashi Iwai from comment #10)
> We need to identify whether the issue comes from XHCI.  For example, try to
> remove xhci-hcd.ko from /lib/modules/$VERSION, rebuild initrd and retest
> multiple times.

Thanks! After removing xhci-hcd.ko
/lib/modules/4.1.13-5-default/kernel/drivers/usb/host/, shutdown worked fine 6
times in a row.

> Once after identifying that the issue is in xhci, you can try quirk option. 

Okay, I will try each of these, one at a time:
options xhci-hcd quirks=270336 
options xhci-hcd quirks=8192
options xhci-hcd quirks=262144

> Above all, this should be reported to upstream as well.

When I have found the minimum set of flags, I would add my hardware and flags
as a comment to https://bugzilla.kernel.org/show_bug.cgi?id=66171 ?