diff --git a/EdkModulePkg/Bus/Pci/PciBus/Dxe/PciDeviceSupport.c b/EdkModulePkg/Bus/Pci/PciBus/Dxe/PciDeviceSupport.c
index b1cee26c0a..df69078e77 100644
--- a/EdkModulePkg/Bus/Pci/PciBus/Dxe/PciDeviceSupport.c
+++ b/EdkModulePkg/Bus/Pci/PciBus/Dxe/PciDeviceSupport.c
@@ -283,28 +283,29 @@ RegisterPciDevice (
 
 Routine Description:
 
-  This function is used to register the PCI device to the EFI,
-  create a handle for this PCI device,then attach apporpriate protocols
-  onto the handle.
+  This function registers the PCI IO device. It creates a handle for this PCI IO device 
+  (if the handle does not exist), attaches appropriate protocols onto the handle, does
+  necessary initialization, and sets up parent/child relationship with its bus controller.
 
 Arguments:
 
-  Controller    - An efi handle.
-  PciIoDevice   - A pointer to the PCI_IO_DEVICE.
-  Handle        - A pointer to a efi handle.
+  Controller    - An EFI handle for the PCI bus controller.
+  PciIoDevice   - A PCI_IO_DEVICE pointer to the PCI IO device to be registered.
+  Handle        - A pointer to hold the EFI handle for the PCI IO device.
 
 Returns:
 
-  None
+  EFI_SUCCESS   - The PCI device is successfully registered.
+  Others        - An error occurred when registering the PCI device.
 
 --*/
-// TODO:    EFI_SUCCESS - add return value to function comment
 {
   EFI_STATUS          Status;
   VOID                *PlatformOpRomBuffer;
   UINTN               PlatformOpRomSize;
   UINT8               PciExpressCapRegOffset;
   EFI_PCI_IO_PROTOCOL *PciIo;
+  UINT8               Data8;
 
   //
   // Install the pciio protocol, device path protocol
@@ -326,21 +327,22 @@ Returns:
   //
   PciExpressCapRegOffset = 0;
   Status = LocateCapabilityRegBlock (
-            PciIoDevice,
-            EFI_PCI_CAPABILITY_ID_PCIEXP,
-            &PciExpressCapRegOffset,
-            NULL
-            );
+             PciIoDevice,
+             EFI_PCI_CAPABILITY_ID_PCIEXP,
+             &PciExpressCapRegOffset,
+             NULL
+             );
   if (!EFI_ERROR (Status)) {
     PciIoDevice->IsPciExp = TRUE;
   }
   
   //
-  // Force Interrupt line to zero for cards that come up randomly
+  // Force Interrupt line to "Unknown" or "No Connection"
   //
   PciIo = &(PciIoDevice->PciIo);
-  PciIo->Pci.Write (PciIo, EfiPciIoWidthUint8, 0x3C, 1, &gAllZero);
-  
+  Data8 = PCI_INT_LINE_UNKNOWN;
+  PciIo->Pci.Write (PciIo, EfiPciIoWidthUint8, 0x3C, 1, &Data8);
+
   //
   // Process Platform OpRom
   //
@@ -348,11 +350,11 @@ Returns:
     PciIoDevice->AllOpRomProcessed = TRUE;
 
     Status = gPciPlatformProtocol->GetPciRom (
-                                    gPciPlatformProtocol,
-                                    PciIoDevice->Handle,
-                                    &PlatformOpRomBuffer,
-                                    &PlatformOpRomSize
-                                    );
+                                     gPciPlatformProtocol,
+                                     PciIoDevice->Handle,
+                                     &PlatformOpRomBuffer,
+                                     &PlatformOpRomSize
+                                     );
 
     if (!EFI_ERROR (Status)) {
 
@@ -382,13 +384,13 @@ Returns:
                     );
     if (EFI_ERROR (Status)) {
       gBS->UninstallMultipleProtocolInterfaces (
-            &PciIoDevice->Handle,
-            &gEfiDevicePathProtocolGuid,
-            PciIoDevice->DevicePath,
-            &gEfiPciIoProtocolGuid,
-            &PciIoDevice->PciIo,
-            NULL
-            );
+             &PciIoDevice->Handle,
+             &gEfiDevicePathProtocolGuid,
+             PciIoDevice->DevicePath,
+             &gEfiPciIoProtocolGuid,
+             &PciIoDevice->PciIo,
+             NULL
+             );
 
       return Status;
     }