From fe1a5ac7d87e86d39d5da38371cd56a2039d8dc3 Mon Sep 17 00:00:00 2001
From: Robert Moore <Robert.Moore@intel.com>
Date: Mon, 9 Jul 2012 12:12:02 -0700
Subject: [PATCH] Remove code to disable bus master arbitration.

This change removes the code to disable/enable bus master
arbitration during suspend/resume. Use of the ARB_DIS
bit in the optional PM2_CNT register causes resume problems
on many machines.
---
 source/components/hardware/hwsleep.c | 34 +++++++++++-----------------
 1 file changed, 13 insertions(+), 21 deletions(-)

diff --git a/source/components/hardware/hwsleep.c b/source/components/hardware/hwsleep.c
index 6fd9d66cd..6fac73e5b 100644
--- a/source/components/hardware/hwsleep.c
+++ b/source/components/hardware/hwsleep.c
@@ -171,19 +171,14 @@ AcpiHwLegacySleep (
         return_ACPI_STATUS (Status);
     }
 
-    if (SleepState != ACPI_STATE_S5)
-    {
-        /*
-         * Disable BM arbitration. This feature is contained within an
-         * optional register (PM2 Control), so ignore a BAD_ADDRESS
-         * exception.
-         */
-        Status = AcpiWriteBitRegister (ACPI_BITREG_ARB_DISABLE, 1);
-        if (ACPI_FAILURE (Status) && (Status != AE_BAD_ADDRESS))
-        {
-            return_ACPI_STATUS (Status);
-        }
-    }
+    /*
+     * Code removed: no longer set the ARB_DIS bit in the PM2_CNT
+     * register when suspending. Use of ARB_DIS causes resume
+     * problems on many machines.
+     *
+     * if (SleepState != ACPI_STATE_S5)
+     *    Status = AcpiWriteBitRegister (ACPI_BITREG_ARB_DISABLE, 1);
+     */
 
     /*
      * 1) Disable/Clear all GPEs
@@ -453,15 +448,12 @@ AcpiHwLegacyWake (
             ACPI_CLEAR_STATUS);
 
     /*
-     * Enable BM arbitration. This feature is contained within an
-     * optional register (PM2 Control), so ignore a BAD_ADDRESS
-     * exception.
+     * Code removed: no longer clear the ARB_DIS bit in the PM2_CNT
+     * register when resuming. Use of ARB_DIS causes resume problems
+     * on many machines.
+     *
+     * Status = AcpiWriteBitRegister (ACPI_BITREG_ARB_DISABLE, 0);
      */
-    Status = AcpiWriteBitRegister (ACPI_BITREG_ARB_DISABLE, 0);
-    if (ACPI_FAILURE (Status) && (Status != AE_BAD_ADDRESS))
-    {
-        return_ACPI_STATUS (Status);
-    }
 
     AcpiHwExecuteSleepMethod (METHOD_PATHNAME__SST, ACPI_SST_WORKING);
     return_ACPI_STATUS (Status);