From 19ca21653362e4deb0533ce343439b1fb514510f Mon Sep 17 00:00:00 2001
From: vit9696 <vit9696@users.noreply.github.com>
Date: Sun, 27 Oct 2024 04:30:33 +0300
Subject: [PATCH] MdeModulePkg/EhciDxe: Fix legacy handoff logic

references acidanthera/bugtracker#2436
---
 MdeModulePkg/Bus/Pci/EhciDxe/EhciReg.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/MdeModulePkg/Bus/Pci/EhciDxe/EhciReg.c b/MdeModulePkg/Bus/Pci/EhciDxe/EhciReg.c
index 912048eee9..fadb25652a 100644
--- a/MdeModulePkg/Bus/Pci/EhciDxe/EhciReg.c
+++ b/MdeModulePkg/Bus/Pci/EhciDxe/EhciReg.c
@@ -309,6 +309,17 @@ EhcClearLegacySupport (
   PciIo->Pci.Read (PciIo, EfiPciIoWidthUint32, ExtendCap, 1, &Value);
   PciIo->Pci.Read (PciIo, EfiPciIoWidthUint32, ExtendCap + 0x4, 1, &Value);
 
+  //
+  // Disable the SMI in USBLEGCTLSTS firstly
+  // Not doing this may result in a hardlock soon after
+  //
+  PciIo->Pci.Read (PciIo, EfiPciIoWidthUint32, ExtendCap + 0x4, 1, &Value);
+  Value &= 0xFFFF0000;
+  PciIo->Pci.Write (PciIo, EfiPciIoWidthUint32, ExtendCap + 0x4, 1, &Value);
+
+  //
+  // Get EHCI Ownership from legacy bios
+  //
   PciIo->Pci.Read (PciIo, EfiPciIoWidthUint32, ExtendCap, 1, &Value);
   Value |= (0x1 << 24);
   PciIo->Pci.Write (PciIo, EfiPciIoWidthUint32, ExtendCap, 1, &Value);