xhci: rework cycle bit checking for new dequeue pointers

commit 365038d83313951d6ace15342eb24624bbef1666 upstream.

When we manually need to move the TR dequeue pointer we need to set the
correct cycle bit as well. Previously we used the trb pointer from the
last event received as a base, but this was changed in
commit 1f81b6d22a59 ("usb: xhci: Prefer endpoint context dequeue pointer")
to use the dequeue pointer from the endpoint context instead

It turns out some Asmedia controllers advance the dequeue pointer
stored in the endpoint context past the event triggering TRB, and
this messed up the way the cycle bit was calculated.

Instead of adding a quirk or complicating the already hard to follow cycle bit
code, the whole cycle bit calculation is now simplified and adapted to handle
event and endpoint context dequeue pointer differences.

Fixes: 1f81b6d22a59 ("usb: xhci: Prefer endpoint context dequeue pointer")
Reported-by: Maciej Puzio <mx34567@gmail.com>
Reported-by: Evan Langlois <uudruid74@gmail.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: Maciej Puzio <mx34567@gmail.com>
Tested-by: Evan Langlois <uudruid74@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2:
 - Debug logging in xhci_find_new_dequeue_state() is slightly different
 - Don't delete find_trb_seg(); it's still needed by xhci_cmd_to_noop()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2 files changed