XhciDxe: Workaround for USB Net driver

Typically, there are two cases that the BMC device returns NAK when receiving a BULK IN request - Case 1: BMC has no data for the Bulk In request - Case 2: BMC is preparing the data for returning to the Host So, I'm adding a workaround for reducing the number of retries for checking Bulk In response from BMC device in the case 1 so that the Host will return Timeout right after receiving a series of 50 sequential NAK responses. Signed-off-by: Nhi Pham <[email protected]>
AmpereComputing · Jun 30, 2021 · ac5f121 · ac5f121
1 parent 4b0c883
commit ac5f121
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diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
@@ -1281,9 +1281,15 @@ XhcBulkTransfer (
              );
 
 ON_EXIT:
+#if 0
+  //
+  // Reduces error messages when there is no data from USB device.
+  //
   if (EFI_ERROR (Status)) {
     DEBUG ((EFI_D_ERROR, "XhcBulkTransfer: error - %r, transfer - %x\n", Status, *TransferResult));
   }
+#endif
+
   gBS->RestoreTPL (OldTpl);
 
   return Status;

diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c b/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
@@ -1322,6 +1322,21 @@ XhcExecTransfer (
     goto DONE;
   }
 
+  //
+  // WORKAROUND - USB Net driver
+  // Typically, there are two cases that the BMC device returns NAK
+  // when receiving a BULK IN request
+  //   - Case 1: BMC has no data for the Bulk In request
+  //   - Case 2: BMC is preparing the data for returning to the Host
+  // So, I'm adding a workaround for reducing the number of retries for
+  // checking Bulk In response from BMC device in the case 1 so that
+  // the Host will return Timeout right after receiving a series of 50
+  // sequential NAK responses.
+  //
+#define MAX_NUMBER_OF_NAK_FOR_A_BULK_IN_REQUEST  50
+  UINTN Count;
+  Count = 0;
+
 RINGDOORBELL:
   XhcRingDoorBell (Xhc, SlotId, Dci);
 
@@ -1331,6 +1346,12 @@ XhcExecTransfer (
       break;
     }
     gBS->Stall (XHC_1_MICROSECOND);
+    if (++Count > MAX_NUMBER_OF_NAK_FOR_A_BULK_IN_REQUEST
+        && Urb->Ep.EpAddr == 1
+        && Urb->Ep.Direction == EfiUsbDataIn
+        && Urb->Ep.Type == XHC_BULK_TRANSFER) {
+      break;
+    }
   } while (IndefiniteTimeout || EFI_ERROR(gBS->CheckEvent (TimeoutEvent)));
 
 DONE: