From: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Date: Wed, 7 Mar 2007 23:29:35 +0000 (-0500)
Subject: ACPI: ec: fix race in status register access
X-Git-Tag: v2.6.21-rc4~56^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9e197219605513c14d3eae41039ecf1b82d1920d;p=pandora-kernel.git

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>
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