tree 5f16a44dfe811d8402615b151825f6853663c366
parent c2abb4d0dad6ed00e1e230d604c4c0a76eb4eef7
author Duncan Laurie <dlaurie@chromium.org> 1380037644 -0700
committer Duncan Laurie <dlaurie@chromium.org> 1380039117 +0000

lynxpoint: work around XHCI resume issues

When USB3 devices are attached while in suspend, or two USB3 devices
that are both plugged in are switched to the other port while in
suspend the kernel does not seem to notice this -- despite the cold
attach status bit.  This results in the devices showing up in the USB
list at the old enumerated device numbers and higher layers continuing
to think they are present but not reseponding.

With the kernel workaround to deal with devices that are logically
disconnected it is possible for firmware to send a warm port reset to
devices that are in this state and then the kernel will see them disappear
and handle it properly.

This same issue exists in the EFI firmware on the Whitetip Mountain 2
reference board so it is not specifically a coreboot bug.  If this
behavior is fixed in the kernel then this workaround could be removed
since it is in RW firmware.

BUG=chrome-os-partner:22818
BRANCH=falco,peppy,wolf,leon
TEST=manual:

1) attach two USB3 devices
2) suspend system
3) switch the ports that the USB3 devices are attatched to
4) resume system
5) confirm that the devices are re-enumerated and come up properly

Change-Id: Ifba3ffc94a06dc0b2436d7d7d464d824657362af
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/170335
Reviewed-by: Aaron Durbin <adurbin@chromium.org>