[edk2-staging/UEFI_PCI_ENHANCE-2 PATCH 04/15] MdeModulePkg/PciBusDxe: Refactor the PCIe Bridge enable

["Javeed, Ashraf" <ashraf.javeed@intel.com>]

REF:
  https://bugzilla.tianocore.org/show_bug.cgi?id=1954
  https://bugzilla.tianocore.org/show_bug.cgi?id=2194
  https://bugzilla.tianocore.org/show_bug.cgi?id=2313
  https://bugzilla.tianocore.org/show_bug.cgi?id=2499
  https://bugzilla.tianocore.org/show_bug.cgi?id=2500

Refactor the PCIe Bridge enabling code.

Signed-off-by: Ashraf Javeed <ashraf.javeed@intel.com>
Signed-off-by: Ray Ni <ray.ni@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
---
 MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c | 70 ++++++++++++++++++++--------------------------------------------------
 1 file changed, 20 insertions(+), 50 deletions(-)

diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c
index 5724fd6..62ef184 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciDeviceSupport.c
@@ -597,52 +597,36 @@ DeRegisterPciDevice (
 }
 
 /**
-  Start the PCI root Ports or PCI-PCI Bridge only.
+  Enable all the PCI bridges under the specified root bridge or PCI-PCI Bridge.
 
-  @param Controller          The root bridge handle.
-  @param RootBridge          A pointer to the PCI_IO_DEVICE.
-  @param RemainingDevicePath A pointer to the EFI_DEVICE_PATH_PROTOCOL.
-  @param NumberOfChildren    Children number.
-  @param ChildHandleBuffer   A pointer to the child handle buffer.
-
-  @retval EFI_NOT_READY   Device is not allocated.
-  @retval EFI_UNSUPPORTED Device only support PCI-PCI bridge.
-  @retval EFI_NOT_FOUND   Can not find the specific device.
-  @retval EFI_SUCCESS     Success to start Pci devices on bridge.
+  @param Bridge          A pointer to the PCI_IO_DEVICE.
 
 **/
-EFI_STATUS
+VOID
 EnablePciBridges (
-  IN EFI_HANDLE                          Controller,
-  IN PCI_IO_DEVICE                       *RootBridge
+  IN PCI_IO_DEVICE          *Bridge
   )
 
 {
   PCI_IO_DEVICE             *PciIoDevice;
-  EFI_STATUS                Status;
-  LIST_ENTRY                *CurrentLink;
+  LIST_ENTRY                *Link;
   UINT64                    Supports;
 
-  PciIoDevice = NULL;
-  CurrentLink = RootBridge->ChildList.ForwardLink;
-
-  while (CurrentLink != NULL && CurrentLink != &RootBridge->ChildList) {
-
-    PciIoDevice = PCI_IO_DEVICE_FROM_LINK (CurrentLink);
-
+  for ( Link = GetFirstNode (&Bridge->ChildList)
+      ; !IsNull (&Bridge->ChildList, Link)
+      ; Link = GetNextNode (&Bridge->ChildList, Link)
+      ) {
+    PciIoDevice = PCI_IO_DEVICE_FROM_LINK (Link);
     //
-    // check if the device has been assigned with required resource
-    // and registered
+    // Skip the device hasn't been assigned with required resource
+    // or registered.
     //
-    if (!PciIoDevice->Registered && !PciIoDevice->Allocated) {
-      return EFI_NOT_READY;
+    if (!PciIoDevice->Registered || !PciIoDevice->Allocated) {
+      continue;
     }
 
     if (IS_PCI_BRIDGE (&PciIoDevice->Pci)) {
-      Status = EnablePciBridges (
-                 Controller,
-                 PciIoDevice
-                 );
+      EnablePciBridges (PciIoDevice);
 
       PciIoDevice->PciIo.Attributes (
                            &(PciIoDevice->PciIo),
@@ -650,27 +634,17 @@ EnablePciBridges (
                            0,
                            &Supports
                          );
-      Supports &= (UINT64)EFI_PCI_DEVICE_ENABLE;
+      Supports &= (UINT64) EFI_PCI_DEVICE_ENABLE;
       PciIoDevice->PciIo.Attributes (
                            &(PciIoDevice->PciIo),
                            EfiPciIoAttributeOperationEnable,
                            Supports,
                            NULL
                          );
-
     }
-
-    CurrentLink = CurrentLink->ForwardLink;
-  }
-
-  if (PciIoDevice == NULL) {
-    return EFI_NOT_FOUND;
-  } else {
-    return EFI_SUCCESS;
   }
 }
 
-
 /**
   Register to manage the PCI device on the specified root bridge or PCI-PCI Bridge.
 
@@ -851,9 +825,7 @@ StartPciDevicesOnBridge (
              ChildHandleBuffer
              );
 
-  if (EFI_ERROR (Status)) {
-    return Status;
-  } else {
+  if (!EFI_ERROR (Status)) {
     //
     // the late configuration of PCI Express features
     // the platform is required to indicate its requirement for the initialization
@@ -861,13 +833,11 @@ StartPciDevicesOnBridge (
     //
 
     //
-    // finally start those PCI bridge port devices only
+    // finally enable those PCI bridges
     //
-    return EnablePciBridges (
-             Controller,
-             RootBridge
-             );
+    EnablePciBridges (RootBridge);
   }
+  return Status;
 }
 
 /**
-- 
2.21.0.windows.1