Hi Mathias,
This is a follow-up patch for below comment
"rebase OGAWA Hirofumi's changes on top of that, and send to usb-linus only"
in below discussion thread.
https://lkml.org/lkml/2016/12/21/186
I rebased the patch and added unlock-before and lock-after xhci->lock during
waiting for the command stopped event.