From 052a04e610a38936b0e7d6100a8af8c8b90f7a4d Mon Sep 17 00:00:00 2001
From: CamilleLaVey <camillelavey99@gmail.com>
Date: Thu, 17 Sep 2026 02:20:40 -0400
Subject: [PATCH] Correcting some bugs on the vulkan async presentation thread

---
 .../renderer_vulkan/renderer_vulkan.cpp       |  6 +++--
 .../renderer_vulkan/vk_present_manager.cpp    | 26 ++++++++++++++++++-
 .../renderer_vulkan/vk_present_manager.h      | 10 ++++++-
 3 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/src/video_core/renderer_vulkan/renderer_vulkan.cpp b/src/video_core/renderer_vulkan/renderer_vulkan.cpp
index 4fd4c0233b..27ca531186 100644
--- a/src/video_core/renderer_vulkan/renderer_vulkan.cpp
+++ b/src/video_core/renderer_vulkan/renderer_vulkan.cpp
@@ -217,13 +217,15 @@ void RendererVulkan::Composite(std::span<const Tegra::FramebufferConfig> framebu
 
     scheduler.RequestOutsideRenderPassOperationContext();
     blit_swapchain.DrawToFrame(device, rasterizer, frame, framebuffers,
-                               render_window.GetFramebufferLayout(), swapchain.GetImageCount(),
+                               render_window.GetFramebufferLayout(),
+                               present_manager.SwapchainImageCount(),
                                swapchain.GetImageViewFormat());
 
 #ifdef HAS_LSFG
     void(frame_gen.WantedGenerations(present_manager.MaxExtraFrames()));
 
-    frame_gen.Process(device, frame, swapchain.GetImageFormat(), GuestExtent(framebuffers));
+    frame_gen.Process(device, frame, present_manager.SwapchainImageFormat(),
+                      GuestExtent(framebuffers));
 
     const size_t generated_frames = frame_gen.GeneratedFrameCount();
     for (size_t generation = 0; generation < generated_frames; ++generation) {
diff --git a/src/video_core/renderer_vulkan/vk_present_manager.cpp b/src/video_core/renderer_vulkan/vk_present_manager.cpp
index d173a3ba5f..9298764546 100644
--- a/src/video_core/renderer_vulkan/vk_present_manager.cpp
+++ b/src/video_core/renderer_vulkan/vk_present_manager.cpp
@@ -23,6 +23,7 @@ namespace Vulkan {
 namespace {
 
 constexpr size_t MAX_FRAMES_IN_FLIGHT = 7;
+constexpr u32 MAX_PRESENT_ATTEMPTS = 3;
 #ifdef HAS_LSFG
 static_assert(MAX_FRAMES_IN_FLIGHT <= LSFG_MAX_TARGETS);
 #endif
@@ -372,12 +373,33 @@ void PresentManager::SetImageCount() {
 #else
     image_count = std::min<size_t>(swapchain.GetImageCount(), MAX_FRAMES_IN_FLIGHT);
 #endif
+    swapchain_image_count = swapchain.GetImageCount();
+    swapchain_image_format = swapchain.GetImageFormat();
+}
+
+void PresentManager::DiscardFrame(Frame* frame) {
+    static constexpr VkPipelineStageFlags wait_stage = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
+    const VkSemaphore render_ready = *frame->render_ready;
+    const VkSubmitInfo submit_info{
+        .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
+        .pNext = nullptr,
+        .waitSemaphoreCount = 1U,
+        .pWaitSemaphores = &render_ready,
+        .pWaitDstStageMask = &wait_stage,
+        .commandBufferCount = 0U,
+        .pCommandBuffers = nullptr,
+        .signalSemaphoreCount = 0U,
+        .pSignalSemaphores = nullptr,
+    };
+
+    std::scoped_lock submit_lock{scheduler.submit_mutex};
+    void(device.GetGraphicsQueue().Submit(submit_info, *frame->present_done));
 }
 
 void PresentManager::CopyToSwapchain(Frame* frame) {
     bool requires_recreation = false;
 
-    while (true) {
+    for (u32 attempt = 0; attempt < MAX_PRESENT_ATTEMPTS; ++attempt) {
         try {
             // Recreate surface and swapchain if needed.
             if (requires_recreation) {
@@ -397,6 +419,8 @@ void PresentManager::CopyToSwapchain(Frame* frame) {
             requires_recreation = true;
         }
     }
+
+    DiscardFrame(frame);
 }
 
 void PresentManager::CopyToSwapchainImpl(Frame* frame) {
diff --git a/src/video_core/renderer_vulkan/vk_present_manager.h b/src/video_core/renderer_vulkan/vk_present_manager.h
index 4741c55e61..ab2b76f10f 100644
--- a/src/video_core/renderer_vulkan/vk_present_manager.h
+++ b/src/video_core/renderer_vulkan/vk_present_manager.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <atomic>
 #include <condition_variable>
 #include <mutex>
 #include <boost/container/deque.hpp>
@@ -68,6 +69,9 @@ public:
     /// How many additional frames can be queued without stalling the render thread
     [[nodiscard]] size_t MaxExtraFrames() const;
 
+    [[nodiscard]] std::size_t SwapchainImageCount() const { return swapchain_image_count; }
+    [[nodiscard]] VkFormat SwapchainImageFormat() const { return swapchain_image_format; }
+
 private:
     void PresentThread(std::stop_token token);
 
@@ -77,6 +81,8 @@ private:
 
     void RecreateSwapchain(Frame* frame);
 
+    void DiscardFrame(Frame* frame);
+
     void SetImageCount();
 
 private:
@@ -100,7 +106,9 @@ private:
     bool blit_supported;
     bool storage_supported;
     bool use_present_thread;
-    std::size_t image_count{};
+    std::atomic<std::size_t> image_count{};
+    std::atomic<std::size_t> swapchain_image_count{};
+    std::atomic<VkFormat> swapchain_image_format{};
 };
 
 } // namespace Vulkan