[PATCH 2/2] MdeModulePkg/PciBus: Revert "Enable BM on P2P bridges on demand"

[Ruiyu Ni <ruiyu.ni@intel.com>]

This reverts commit 5db417ed2522367290c365831f9d6628d31c346c.
 "MdeModulePkg/PciBusDxe: Enable Bus Master on P2P bridges on demand"

We met some compatibility issues when doing Windows S4 resume.
Reverting the BME disabling patches to fix the S4 resume issue.

Signed-off-by: Ruiyu Ni <Ruiyu.ni@intel.com>
Signed-off-by: Michael Turner <michael.turner@microsoft.com>
Cc: Michael D Kinney <Michael.d.kinney@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
---
 MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c     | 16 +++-------------
 MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c | 18 +++---------------
 MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c                |  8 ++++----
 3 files changed, 10 insertions(+), 32 deletions(-)

diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c
index 97bb971a59..e76c8f0046 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c
@@ -1,7 +1,7 @@
 /** @file
   Supporting functions implementaion for PCI devices management.
 
-Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2015, 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
@@ -711,12 +711,7 @@ StartPciDevicesOnBridge (
                              0,
                              &Supports
                              );
-        //
-        // By default every bridge's IO and MMIO spaces are enabled.
-        // Bridge's Bus Master will be enabled when any device behind it requests
-        // to enable Bus Master.
-        //
-        Supports &= (UINT64) (EFI_PCI_IO_ATTRIBUTE_IO | EFI_PCI_IO_ATTRIBUTE_MEMORY);
+        Supports &= (UINT64)EFI_PCI_DEVICE_ENABLE;
         PciIoDevice->PciIo.Attributes (
                              &(PciIoDevice->PciIo),
                              EfiPciIoAttributeOperationEnable,
@@ -768,12 +763,7 @@ StartPciDevicesOnBridge (
                              0,
                              &Supports
                              );
-        //
-        // By default every bridge's IO and MMIO spaces are enabled.
-        // Bridge's Bus Master will be enabled when any device behind it requests
-        // to enable Bus Master.
-        //
-        Supports &= (UINT64) (EFI_PCI_IO_ATTRIBUTE_IO | EFI_PCI_IO_ATTRIBUTE_MEMORY);
+        Supports &= (UINT64)EFI_PCI_DEVICE_ENABLE;
         PciIoDevice->PciIo.Attributes (
                              &(PciIoDevice->PciIo),
                              EfiPciIoAttributeOperationEnable,
diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
index f73756a31e..81171c82d9 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
@@ -1218,12 +1218,11 @@ DetermineDeviceAttribute (
       return Status;
     }
     //
-    // Assume the PCI Root Bridge supports DAC and Bus Master.
+    // Assume the PCI Root Bridge supports DAC
     //
     PciIoDevice->Supports |= (UINT64)(EFI_PCI_IO_ATTRIBUTE_EMBEDDED_DEVICE |
                               EFI_PCI_IO_ATTRIBUTE_EMBEDDED_ROM |
-                              EFI_PCI_IO_ATTRIBUTE_DUAL_ADDRESS_CYCLE |
-                              EFI_PCI_IO_ATTRIBUTE_BUS_MASTER);
+                              EFI_PCI_IO_ATTRIBUTE_DUAL_ADDRESS_CYCLE);
 
   } else {
 
@@ -1234,16 +1233,9 @@ DetermineDeviceAttribute (
     //
     Command = EFI_PCI_COMMAND_IO_SPACE     |
               EFI_PCI_COMMAND_MEMORY_SPACE |
+              EFI_PCI_COMMAND_BUS_MASTER   |
               EFI_PCI_COMMAND_VGA_PALETTE_SNOOP;
 
-    //
-    // Per PCI-to-PCI Bridge Architecture all PCI-to-PCI bridges are Bus Master capable.
-    // So only test the Bus Master capability for PCI devices.
-    //
-    if (!IS_PCI_BRIDGE(&PciIoDevice->Pci)) {
-      Command |= EFI_PCI_COMMAND_BUS_MASTER;
-    }
-
     BridgeControl = EFI_PCI_BRIDGE_CONTROL_ISA | EFI_PCI_BRIDGE_CONTROL_VGA | EFI_PCI_BRIDGE_CONTROL_VGA_16;
 
     //
@@ -1253,11 +1245,7 @@ DetermineDeviceAttribute (
 
     //
     // Set the supported attributes for specified PCI device
-    // Per PCI-to-PCI Bridge Architecture all PCI-to-PCI bridges are Bus Master capable.
     //
-    if (IS_PCI_BRIDGE(&PciIoDevice->Pci)) {
-      Command |= EFI_PCI_COMMAND_BUS_MASTER;
-    }
     PciSetDeviceAttribute (PciIoDevice, Command, BridgeControl, EFI_SET_SUPPORTS);
 
     //
diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c
index 659f480d71..cc7125e4fc 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c
@@ -1348,8 +1348,7 @@ ModifyRootBridgeAttributes (
   //
   Attributes &= ~(UINT64)(EFI_PCI_IO_ATTRIBUTE_EMBEDDED_DEVICE |
                           EFI_PCI_IO_ATTRIBUTE_EMBEDDED_ROM |
-                          EFI_PCI_IO_ATTRIBUTE_DUAL_ADDRESS_CYCLE |
-                          EFI_PCI_IO_ATTRIBUTE_BUS_MASTER);
+                          EFI_PCI_IO_ATTRIBUTE_DUAL_ADDRESS_CYCLE);
 
   //
   // Record the new attribute of the Root Bridge
@@ -1727,11 +1726,12 @@ PciIoAttributes (
   }
   //
   // The upstream bridge should be also set to revelant attribute
-  // expect for IO and Mem
+  // expect for IO, Mem and BusMaster
   //
   UpStreamAttributes = Attributes &
                        (~(EFI_PCI_IO_ATTRIBUTE_IO     |
-                          EFI_PCI_IO_ATTRIBUTE_MEMORY
+                          EFI_PCI_IO_ATTRIBUTE_MEMORY |
+                          EFI_PCI_IO_ATTRIBUTE_BUS_MASTER
                           )
                         );
   UpStreamBridge = PciIoDevice->Parent;
-- 
2.15.0.gvfs.1.preview.4