From 38156c9f7f69a0b806231539a7286368a284534d Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Mon, 13 Mar 2023 22:56:28 -0500
Subject: [PATCH] Default to D3D11VA on multi-GPU systems

---
 .../video/ffmpeg-renderers/dxva2.cpp          | 33 +++++++++++++++----
 app/streaming/video/ffmpeg-renderers/dxva2.h  |  1 +
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/app/streaming/video/ffmpeg-renderers/dxva2.cpp b/app/streaming/video/ffmpeg-renderers/dxva2.cpp
index 4d4c040a..b8807b63 100644
--- a/app/streaming/video/ffmpeg-renderers/dxva2.cpp
+++ b/app/streaming/video/ffmpeg-renderers/dxva2.cpp
@@ -392,6 +392,14 @@ bool DXVA2Renderer::initializeDeviceQuirks()
     if (SUCCEEDED(hr)) {
         D3DCAPS9 caps;
 
+        UINT adapterCount = d3d9->GetAdapterCount();
+        if (adapterCount > 1) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                        "Detected multi-GPU system with %d GPUs",
+                        adapterCount);
+            m_DeviceQuirks |= DXVA2_QUIRK_MULTI_GPU;
+        }
+
         hr = m_Device->GetDeviceCaps(&caps);
         if (SUCCEEDED(hr)) {
             D3DADAPTER_IDENTIFIER9 id;
@@ -767,7 +775,8 @@ bool DXVA2Renderer::initialize(PDECODER_PARAMETERS params)
     }
 
     // If we have a WDDM 2.0 or later display driver and we're not running in
-    // full-screen exclusive mode, prefer the D3D11VA renderer.
+    // full-screen exclusive mode (or we're on a multi-GPU system in FSE),
+    // prefer the D3D11VA renderer.
     //
     // D3D11VA is better in this case because it can enable tearing in non-FSE
     // modes when the user has V-Sync disabled. In non-FSE V-Sync cases, D3D11VA
@@ -775,15 +784,27 @@ bool DXVA2Renderer::initialize(PDECODER_PARAMETERS params)
     // in windowed mode. When using D3D9, DWM will not promote us to IFlip unless
     // we're full-screen (exclusive or not).
     //
+    // We prefer D3D11VA in FSE multi-GPU cases due to a plethora of issues with
+    // D3D9Ex PresentEx()/D3DPRESENT_DONOTWAIT on hybrid graphics systems (See
+    // issues #235, #240, #386, and #951 on GitHub). Clearly this codepath is not
+    // well tested by Microsoft or GPU vendors, so stick to the more common
+    // D3D11-based renderer which is much more likely to behave.
+    //
     // NB: The reason we only do this for WDDM 2.0 and later is because older
     // AMD drivers (such as those for the HD 5570) render garbage when using
     // the D3D11VA renderer.
     if (m_DecoderSelectionPass == 0 &&
-            (m_DeviceQuirks & DXVA2_QUIRK_WDDM_20_PLUS) &&
-            !((SDL_GetWindowFlags(params->window) & SDL_WINDOW_FULLSCREEN_DESKTOP) == SDL_WINDOW_FULLSCREEN)) {
-        SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
-                    "Defaulting to D3D11VA for non-FSE mode");
-        return false;
+            (m_DeviceQuirks & DXVA2_QUIRK_WDDM_20_PLUS)) {
+        if (!((SDL_GetWindowFlags(params->window) & SDL_WINDOW_FULLSCREEN_DESKTOP) == SDL_WINDOW_FULLSCREEN)) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                        "Defaulting to D3D11VA for non-FSE mode");
+            return false;
+        }
+        else if (m_DeviceQuirks & DXVA2_QUIRK_MULTI_GPU) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                        "Defaulting to D3D11VA for multi-GPU FSE mode");
+            return false;
+        }
     }
 
     if (!initializeDecoder()) {
diff --git a/app/streaming/video/ffmpeg-renderers/dxva2.h b/app/streaming/video/ffmpeg-renderers/dxva2.h
index a2e23cb3..f617beca 100644
--- a/app/streaming/video/ffmpeg-renderers/dxva2.h
+++ b/app/streaming/video/ffmpeg-renderers/dxva2.h
@@ -81,5 +81,6 @@ private:
 #define DXVA2_QUIRK_NO_VP 0x01
 #define DXVA2_QUIRK_SET_DEST_FORMAT 0x02
 #define DXVA2_QUIRK_WDDM_20_PLUS 0x04
+#define DXVA2_QUIRK_MULTI_GPU 0x08
     int m_DeviceQuirks;
 };