From 6dfad339645247c9deb553e4d68e21211ddc61bd Mon Sep 17 00:00:00 2001
From: Lin Ming <ming.m.lin@intel.com>
Date: Mon, 14 Feb 2011 15:29:34 +0800
Subject: ACPICA: GPE detect optimization - ignore unused GPE registers

This optimization will simply ignore GPE registers that contain
no enabled GPEs - there is no need to read the register.
ACPICA bugzilla 884.

http://www.acpica.org/bugzilla/show_bug.cgi?id=884

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/acpica/evgpe.c b/drivers/acpi/acpica/evgpe.c
index 14988a8..67d44ef 100644
--- a/drivers/acpi/acpica/evgpe.c
+++ b/drivers/acpi/acpica/evgpe.c
@@ -373,6 +373,15 @@ u32 acpi_ev_gpe_detect(struct acpi_gpe_xrupt_info * gpe_xrupt_list)
 
 			gpe_register_info = &gpe_block->register_info[i];
 
+			/*
+			 * Optimization: If there are no GPEs enabled within this
+			 * register, we can safely ignore the entire register.
+			 */
+			if (!(gpe_register_info->enable_for_run |
+			      gpe_register_info->enable_for_wake)) {
+				continue;
+			}
+
 			/* Read the Status Register */
 
 			status =
-- 
cgit v0.10.2