[PATCH v7 1/6] MdeModulePkg/PciHostBridge: io range is not mandatory

["Gerd Hoffmann" <kraxel@redhat.com>]

io range is not mandatory according to pcie spec, so allow
pcie host bridge configurations without io window in case
there are no io reservations.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
---
 MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c
index b20bcd310ad5..354be6dbb313 100644
--- a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c
+++ b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c
@@ -1085,6 +1085,12 @@ NotifyPhase (
               RootBridge->ResAllocNode[Index].Base   = BaseAddress;
               RootBridge->ResAllocNode[Index].Status = ResAllocated;
               DEBUG ((DEBUG_INFO, "Success\n"));
+            } else if ((Index == TypeIo) &&
+                       (RootBridge->Io.Base == MAX_UINT64) &&
+                       (RootBridge->ResAllocNode[Index].Length == 0))
+            {
+              /* I/O is optional on PCIe */
+              DEBUG ((DEBUG_INFO, "Success (PCIe NoIO)\n"));
             } else {
               ReturnStatus = EFI_OUT_OF_RESOURCES;
               DEBUG ((DEBUG_ERROR, "Out Of Resource!\n"));
-- 
2.36.1