From 223aa70171839a7afa7154d975d6035f9626eeb6 Mon Sep 17 00:00:00 2001
From: "Herman S." <429230+has207@users.noreply.github.com>
Date: Sun, 2 Nov 2025 13:00:29 +0900
Subject: [PATCH] [Vulkan] Add semaphor reuse workaround and cvar

---
 src/xenia/ui/vulkan/functions/device_1_0.inc |  1 +
 src/xenia/ui/vulkan/vulkan_presenter.cc      | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/xenia/ui/vulkan/functions/device_1_0.inc b/src/xenia/ui/vulkan/functions/device_1_0.inc
index 02d183375..c2c251131 100644
--- a/src/xenia/ui/vulkan/functions/device_1_0.inc
+++ b/src/xenia/ui/vulkan/functions/device_1_0.inc
@@ -76,6 +76,7 @@ XE_UI_VULKAN_FUNCTION(vkResetDescriptorPool)
 XE_UI_VULKAN_FUNCTION(vkResetFences)
 XE_UI_VULKAN_FUNCTION(vkQueueBindSparse)
 XE_UI_VULKAN_FUNCTION(vkQueueSubmit)
+XE_UI_VULKAN_FUNCTION(vkQueueWaitIdle)
 XE_UI_VULKAN_FUNCTION(vkUnmapMemory)
 XE_UI_VULKAN_FUNCTION(vkUpdateDescriptorSets)
 XE_UI_VULKAN_FUNCTION(vkWaitForFences)
diff --git a/src/xenia/ui/vulkan/vulkan_presenter.cc b/src/xenia/ui/vulkan/vulkan_presenter.cc
index a19722545..7151586c4 100644
--- a/src/xenia/ui/vulkan/vulkan_presenter.cc
+++ b/src/xenia/ui/vulkan/vulkan_presenter.cc
@@ -48,6 +48,11 @@ DEFINE_bool(
     "may present with tearing if frames don't meet the host display refresh "
     "rate.",
     "Vulkan");
+DEFINE_bool(
+    vulkan_semaphore_reuse_workaround, false,
+    "Wait for presentation queue idle before each frame to prevent semaphore "
+    "reuse. May fix rendering issues but causes significant performance loss.",
+    "Vulkan");
 
 namespace xe {
 namespace ui {
@@ -1411,6 +1416,18 @@ Presenter::PaintResult VulkanPresenter::PaintAndPresentImpl(
 
   VkSemaphore acquire_semaphore = paint_submission.acquire_semaphore();
 
+  // WORKAROUND: Wait for presentation queue to be idle to ensure semaphore
+  // from previous present is not in use. This prevents
+  // VUID-vkQueueSubmit-pSignalSemaphores-00067.
+  // The semaphore is unsignaled by vkQueuePresentKHR, not by submission fences,
+  // so we must wait for the present queue specifically.
+  // TODO(has207): Proper fix requires per-swapchain-image semaphores.
+  // See https://docs.vulkan.org/guide/latest/swapchain_semaphore_reuse.html
+  if (cvars::vulkan_semaphore_reuse_workaround) {
+    const VulkanDevice::Queue::Acquisition queue_acquisition =
+        vulkan_device_->AcquireQueue(paint_context_.present_queue_family, 0);
+    dfn.vkQueueWaitIdle(queue_acquisition.queue());
+  }
 
   uint32_t swapchain_image_index;
   VkResult acquire_result = dfn.vkAcquireNextImageKHR(