tree 143f16569165e172efd12d938003a48f61c7de62
parent 08e15e81a40e3241ce93b4a43886f3abda184aa6
author Alexey Starikovskiy <alexey.y.starikovskiy@intel.com> 1173310175 -0500
committer Len Brown <len.brown@intel.com> 1173500183 -0500

ACPI: ec: fix race in status register access

Delay the read of the EC status register until
after the event that caused it occurs -- otherwise
it is possible to read and act on stale status that was
associated with the previous event.

Do this with a perpetually incrementing "event_count" to detect
when a new event occurs and it is safe to read status.

There is no workaround for polling mode -- it is inherently
exposed to reading and acting on stale status, since it
doesn't have an interrupt to tell it the event completed.

http://bugzilla.kernel.org/show_bug.cgi?id=8110

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>