diff --git a/DuetPkg/PciBusNoEnumerationDxe/PciPowerManagement.c b/DuetPkg/PciBusNoEnumerationDxe/PciPowerManagement.c
index 2d9b87ab09..eaeaeb762d 100644
--- a/DuetPkg/PciBusNoEnumerationDxe/PciPowerManagement.c
+++ b/DuetPkg/PciBusNoEnumerationDxe/PciPowerManagement.c
@@ -1,6 +1,6 @@
 /*++
 
-Copyright (c) 2005 - 2006, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2005 - 2012, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials                          
 are licensed and made available under the terms and conditions of the BSD License         
 which accompanies this distribution.  The full text of the license may be found at        
@@ -46,7 +46,7 @@ Returns:
 {
   EFI_STATUS  Status;
   UINT8       PowerManagementRegBlock;
-  UINT16      PMCSR;
+  UINT16      PowerManagementCSR;
 
   PowerManagementRegBlock = 0;
 
@@ -64,18 +64,37 @@ Returns:
   //
   // Turn off the PWE assertion and put the device into D0 State
   //
-  PMCSR = 0x8000;
 
   //
-  // Write PMCSR
+  // Read PMCSR
   //
-  PciIoDevice->PciIo.Pci.Write (
-                          &PciIoDevice->PciIo,
-                          EfiPciIoWidthUint16,
-                          PowerManagementRegBlock + 4,
-                          1,
-                          &PMCSR
-                          );
+  Status = PciIoDevice->PciIo.Pci.Read (
+                                    &PciIoDevice->PciIo,
+                                    EfiPciIoWidthUint16,
+                                    PowerManagementRegBlock + 4,
+                                    1,
+                                    &PowerManagementCSR
+                                    );
+  if (!EFI_ERROR (Status)) {
+    //
+    // Clear PME_Status bit
+    //
+    PowerManagementCSR |= BIT15;
+    //
+    // Clear PME_En bit. PowerState = D0.
+    //
+    PowerManagementCSR &= ~(BIT8 | BIT1 | BIT0);
 
-  return EFI_SUCCESS;
+    //
+    // Write PMCSR
+    //
+    Status = PciIoDevice->PciIo.Pci.Write (
+                                      &PciIoDevice->PciIo,
+                                      EfiPciIoWidthUint16,
+                                      PowerManagementRegBlock + 4,
+                                      1,
+                                      &PowerManagementCSR
+                                      );
+  }
+  return Status;
 }
diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciPowerManagement.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciPowerManagement.c
index d9fbaf7e12..ab655e7657 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciPowerManagement.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciPowerManagement.c
@@ -1,7 +1,7 @@
 /** @file
   Power management support fucntions implementation for PCI Bus module.
 
-Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
@@ -50,19 +50,39 @@ ResetPowerManagementFeature (
   //
   // Turn off the PWE assertion and put the device into D0 State
   //
-  PowerManagementCSR = 0x8000;
 
   //
-  // Write PMCSR
+  // Read PMCSR
   //
-  PciIoDevice->PciIo.Pci.Write (
-                           &PciIoDevice->PciIo,
-                           EfiPciIoWidthUint16,
-                           PowerManagementRegBlock + 4,
-                           1,
-                           &PowerManagementCSR
-                           );
+  Status = PciIoDevice->PciIo.Pci.Read (
+                                    &PciIoDevice->PciIo,
+                                    EfiPciIoWidthUint16,
+                                    PowerManagementRegBlock + 4,
+                                    1,
+                                    &PowerManagementCSR
+                                    );
 
-  return EFI_SUCCESS;
+  if (!EFI_ERROR (Status)) {
+    //
+    // Clear PME_Status bit
+    //
+    PowerManagementCSR |= BIT15;
+    //
+    // Clear PME_En bit. PowerState = D0.
+    //
+    PowerManagementCSR &= ~(BIT8 | BIT1 | BIT0);
+
+    //
+    // Write PMCSR
+    //
+    Status = PciIoDevice->PciIo.Pci.Write (
+                                      &PciIoDevice->PciIo,
+                                      EfiPciIoWidthUint16,
+                                      PowerManagementRegBlock + 4,
+                                      1,
+                                      &PowerManagementCSR
+                                      );
+  }
+  return Status;
 }