Merge pull request #38 from Djihads80/nx2-accuracy-switch

nx2: Fix the current crash when switching from fast to accurate and vice versa

2 files changed, 16 insertions, 5 deletions

diff --git a/src/video_core/dma_pusher.cpp b/src/video_core/dma_pusher.cpp
index 62f7e6bfdb..88d571ae5f 100644
--- a/src/video_core/dma_pusher.cpp
+++ b/src/video_core/dma_pusher.cpp
@@ -151,7 +151,10 @@ bool DmaPusher::Step() {
             }
         }
         // A resumed entry is read again: the words after the acquire may be new by now.
-        const bool use_safe = Settings::IsDMALevelDefault() ? Settings::IsGPULevelHigh() : Settings::IsDMALevelSafe();
+        // A safe read flushes the caches, which belong to the split's back thread while it runs
+        // (the split only starts with unsafe reads; the settings can change mid-game).
+        const bool use_safe = !VideoCommon::GpuSplit::Get().Active() &&
+                              (Settings::IsDMALevelDefault() ? Settings::IsGPULevelHigh() : Settings::IsDMALevelSafe());
         if (use_safe) {
             Tegra::Memory::GpuGuestMemory<Tegra::CommandHeader, Tegra::Memory::GuestMemoryFlags::SafeRead>headers(memory_manager, dma_state.dma_get, header.size, &command_headers);
             const std::span<const CommandHeader> commands{headers.data(), headers.size()};
diff --git a/src/video_core/gpu_split.cpp b/src/video_core/gpu_split.cpp
index 2bc8e29470..ac0d3f25f1 100644
--- a/src/video_core/gpu_split.cpp
+++ b/src/video_core/gpu_split.cpp
@@ -90,15 +90,23 @@ void GpuSplit::MaybeStart(Core::System& system_) {
         return value != nullptr ? value[0] : '2';
     }();
     const bool wanted = mode == '1' || mode == '2';
-    if (active || !wanted || !Tegra::g_nx2_ampere.load(std::memory_order_relaxed)) {
+    if (!wanted || !Tegra::g_nx2_ampere.load(std::memory_order_relaxed)) {
         return;
     }
     // The front reads command lists straight from guest memory; a read that flushes the caches
-    // first (safe DMA, accurate GPU) would touch back-owned state.
+    // first (safe DMA, accurate GPU) would touch back-owned state. The settings can change
+    // mid-game: hand the engines back to the front (and start again when they allow it).
     const bool safe_reads = Settings::IsDMALevelDefault() ? Settings::IsGPULevelHigh()
                                                           : Settings::IsDMALevelSafe();
-    if (safe_reads || Settings::IsGPULevelHigh() ||
-        Settings::values.renderer_backend.GetValue() != Settings::RendererBackend::Vulkan) {
+    const bool allowed = !safe_reads && !Settings::IsGPULevelHigh() &&
+                         Settings::values.renderer_backend.GetValue() == Settings::RendererBackend::Vulkan;
+    if (active && !allowed) {
+        Drain();
+        Stop();
+        LOG_INFO(HW_GPU, "GPU thread split: stopped, the accuracy settings need the caches on the front");
+        return;
+    }
+    if (active || !allowed) {
         return;
     }
     system = &system_;