From 79326184244d51a9f37bb59eb9dac83d4fededc2 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Wed, 14 May 2025 23:09:52 +1000
Subject: [PATCH] Bus: Enable SIO2 on any unknown BIOS

Not all PS2 BIOSes are in the list.
---
 src/core/bus.cpp    | 4 ++--
 src/core/system.cpp | 4 ++--
 src/core/system.h   | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/core/bus.cpp b/src/core/bus.cpp
index 5771d5c5a..a5f326a61 100644
--- a/src/core/bus.cpp
+++ b/src/core/bus.cpp
@@ -1656,7 +1656,7 @@ template<MemoryAccessSize size>
 u32 Bus::SIO2ReadHandler(PhysicalMemoryAddress address)
 {
   // Stub for using PS2 BIOS.
-  if (!System::IsUsingPS2BIOS()) [[unlikely]]
+  if (System::IsUsingKnownPS1BIOS()) [[unlikely]]
   {
     // Throw exception when not using PS2 BIOS.
     return UnmappedReadHandler<size>(address);
@@ -1670,7 +1670,7 @@ template<MemoryAccessSize size>
 void Bus::SIO2WriteHandler(PhysicalMemoryAddress address, u32 value)
 {
   // Stub for using PS2 BIOS.
-  if (!System::IsUsingPS2BIOS()) [[unlikely]]
+  if (System::IsUsingKnownPS1BIOS()) [[unlikely]]
   {
     // Throw exception when not using PS2 BIOS.
     UnmappedWriteHandler<size>(address, value);
diff --git a/src/core/system.cpp b/src/core/system.cpp
index 702256e86..8fbc21ad6 100644
--- a/src/core/system.cpp
+++ b/src/core/system.cpp
@@ -795,9 +795,9 @@ System::BootMode System::GetBootMode()
   return s_state.boot_mode;
 }
 
-bool System::IsUsingPS2BIOS()
+bool System::IsUsingKnownPS1BIOS()
 {
-  return (s_state.bios_image_info && s_state.bios_image_info->fastboot_patch == BIOS::ImageInfo::FastBootPatch::Type2);
+  return (s_state.bios_image_info && s_state.bios_image_info->fastboot_patch == BIOS::ImageInfo::FastBootPatch::Type1);
 }
 
 bool System::IsDiscPath(std::string_view path)
diff --git a/src/core/system.h b/src/core/system.h
index 3e9de9cb0..359caaba2 100644
--- a/src/core/system.h
+++ b/src/core/system.h
@@ -226,7 +226,7 @@ const std::string& GetExeOverride();
 const GameDatabase::Entry* GetGameDatabaseEntry();
 GameHash GetGameHash();
 bool IsRunningUnknownGame();
-bool IsUsingPS2BIOS();
+bool IsUsingKnownPS1BIOS();
 BootMode GetBootMode();
 
 /// Returns the time elapsed in the current play session.