From 73f26383219604935ac6d548103531a12b73a896 Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Sat, 26 Oct 2024 00:39:24 +0200
Subject: [PATCH] [dxgi] Pass refresh rate to swap chains if latency control is
 enabled

---
 src/dxgi/dxgi_options.cpp   | 1 +
 src/dxgi/dxgi_options.h     | 3 +++
 src/dxgi/dxgi_swapchain.cpp | 6 +++++-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/dxgi/dxgi_options.cpp b/src/dxgi/dxgi_options.cpp
index 0881279a5..81cc887e5 100644
--- a/src/dxgi/dxgi_options.cpp
+++ b/src/dxgi/dxgi_options.cpp
@@ -91,6 +91,7 @@ namespace dxvk {
     this->maxSharedMemory = VkDeviceSize(config.getOption<int32_t>("dxgi.maxSharedMemory", 0)) << 20;
 
     this->maxFrameRate = config.getOption<int32_t>("dxgi.maxFrameRate", 0);
+    this->maxFrameLatency = config.getOption<int32_t>("dxgi.maxFrameLatency", 0);
     this->syncInterval = config.getOption<int32_t>("dxgi.syncInterval", -1);
 
     // Expose Nvidia GPUs properly if NvAPI is enabled in environment
diff --git a/src/dxgi/dxgi_options.h b/src/dxgi/dxgi_options.h
index 1cd170210..3f412e093 100644
--- a/src/dxgi/dxgi_options.h
+++ b/src/dxgi/dxgi_options.h
@@ -49,6 +49,9 @@ namespace dxvk {
     /// Limit frame rate
     int32_t maxFrameRate;
 
+    /// Control frame latency
+    int32_t maxFrameLatency;
+
     /// Sync interval. Overrides the value
     /// passed to IDXGISwapChain::Present.
     int32_t syncInterval;
diff --git a/src/dxgi/dxgi_swapchain.cpp b/src/dxgi/dxgi_swapchain.cpp
index 67e2a54cd..924be5a40 100644
--- a/src/dxgi/dxgi_swapchain.cpp
+++ b/src/dxgi/dxgi_swapchain.cpp
@@ -1003,7 +1003,11 @@ namespace dxvk {
       m_frameRateSyncInterval = SyncInterval;
       m_frameRateRefresh = 0.0f;
 
-      if (SyncInterval > 1 && wsi::isWindow(m_window)) {
+      // Frame latency control can only work on windowed or borderless swap
+      // chains if the presenter is aware of the display refresh rate
+      UINT minSyncInterval = (m_factory->GetOptions()->maxFrameLatency < 0 && !m_is_d3d12) ? 0 : 1;
+
+      if (SyncInterval > minSyncInterval && wsi::isWindow(m_window)) {
         wsi::WsiMode mode = { };
 
         if (wsi::getCurrentDisplayMode(wsi::getWindowMonitor(m_window), &mode)) {