From afdbe90992bf4d4388b2560e309dd44c22b8ca8a Mon Sep 17 00:00:00 2001
From: PavelBARABANOV <pavelbarabanov94@gmail.com>
Date: Sun, 22 Feb 2026 01:56:16 +0300
Subject: [PATCH] [vk] Fix lost wakeup in fence mode using atomic wait

---
 .../renderer_vulkan/vk_master_semaphore.cpp   | 40 +++++++------------
 .../renderer_vulkan/vk_master_semaphore.h     |  1 +
 2 files changed, 15 insertions(+), 26 deletions(-)

diff --git a/src/video_core/renderer_vulkan/vk_master_semaphore.cpp b/src/video_core/renderer_vulkan/vk_master_semaphore.cpp
index a82e2c73fa..0e92902669 100644
--- a/src/video_core/renderer_vulkan/vk_master_semaphore.cpp
+++ b/src/video_core/renderer_vulkan/vk_master_semaphore.cpp
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
@@ -78,11 +78,17 @@ void MasterSemaphore::Refresh() {
 
 void MasterSemaphore::Wait(u64 tick) {
     if (!semaphore) {
-        // If we don't support timeline semaphores, wait for the value normally
-        std::unique_lock lk{free_mutex};
-        free_cv.wait(lk, [&] {
-            return gpu_tick.load(std::memory_order_acquire) >= tick;
-        });
+        // Fast check: already reached the requested tick?
+        if (gpu_tick.load(std::memory_order_acquire) >= tick) {
+            return;
+        }
+
+        // Wait for fence completions using atomic wait
+        u64 last_notify = notify_counter.load(std::memory_order_relaxed);
+        while (gpu_tick.load(std::memory_order_acquire) < tick) {
+            notify_counter.wait(last_notify, std::memory_order_acquire);
+            last_notify = notify_counter.load(std::memory_order_relaxed);
+        }
         return;
     }
 
@@ -217,33 +223,15 @@ void MasterSemaphore::WaitThread(std::stop_token token) {
             std::tie(host_tick, fence) = std::move(wait_queue.front());
             wait_queue.pop();
         }
-
-#ifdef ANDROID
-        VkResult status;
-        do {
-            status = fence.GetStatus();
-            if (status == VK_NOT_READY) {
-                std::this_thread::sleep_for(std::chrono::microseconds(100));
-            }
-        } while (status == VK_NOT_READY);
-
-        if (status == VK_SUCCESS) {
-            fence.Reset();
-        } else {
-            vk::Check(status);
-            continue;
-        }
-#else
         fence.Wait();
         fence.Reset();
-#endif
-
         {
             std::scoped_lock lock{free_mutex};
             free_queue.push_front(std::move(fence));
             gpu_tick.store(host_tick, std::memory_order_release);
+            notify_counter.fetch_add(1, std::memory_order_release);
         }
-        free_cv.notify_all();
+        notify_counter.notify_one();
     }
 }
 
diff --git a/src/video_core/renderer_vulkan/vk_master_semaphore.h b/src/video_core/renderer_vulkan/vk_master_semaphore.h
index 7dfb93ffbf..997c2a180c 100644
--- a/src/video_core/renderer_vulkan/vk_master_semaphore.h
+++ b/src/video_core/renderer_vulkan/vk_master_semaphore.h
@@ -72,6 +72,7 @@ private:
     vk::Semaphore semaphore;          ///< Timeline semaphore.
     std::atomic<u64> gpu_tick{0};     ///< Current known GPU tick.
     std::atomic<u64> current_tick{1}; ///< Current logical tick.
+    std::atomic<u64> notify_counter{0}; ///< Fence completion counter for atomic wait.
     std::mutex wait_mutex;
     std::mutex free_mutex;
     std::condition_variable free_cv;