Fix Vulkan 9-screen tiling and flashing textures on Android (Samsung One UI / Adreno 740)

Root cause: Window.SetSustainedPerformanceMode(true) triggered a Samsung One UI
display-mode transition that recreated the SurfaceView as RGB565. The reactive
SurfaceChanged guard called SetFormat(RGBA8888) causing a second teardown. During
that teardown, the ANativeWindow transiently reported scaled (dp) dimensions
(1029×480 on a 3088×1440 3×-density panel). Veldrid baked those as the permanent
swapchain size → 3×3 tiling, blurry textures, and ~40fps.

Fixes:
- Remove SetSustainedPerformanceMode(true) entirely; ADPF is covered by Oboe's
  setPerformanceHintEnabled and GC latency by AndroidHighPerformanceSessionManager
- Add proactive Window.SetFormat(RGBA8888) before base.OnCreate() so SDL's
  SurfaceView is born with RGBA8888, eliminating the startup teardown
- Upgrade reactive SurfaceChanged guard to also log to Runtime (not just
  Performance) so any future mid-session RGB565 resets are immediately visible
- Update all stale comments that referenced SustainedPerformanceMode

Agent-Logs-Url: https://github.com/winnerspiros/osu/sessions/3c1fa36e-ab75-466a-9437-b218eeb9fa8e

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: Copilot

osu.Android/OsuGameActivity.cs

@@ -225,6 +225,29 @@ protected override void OnCreate(Bundle? savedInstanceState)
             LogManagement.WipeShaderCacheOnceForVersion();
             CrashDiagnostics.WriteAliveMarker("LogManagement.WipeShaderCacheOnceForVersion (returned)");
 
+            // Stamp RGBA8888 at the Window level BEFORE SDL creates its SurfaceView inside
+            // base.OnCreate(). Android's default SurfaceView pixel format on many high-density
+            // Samsung / Qualcomm panels is RGB565. SDL3 only calls SurfaceHolder.setFormat(
+            // RGBA8888) for the OpenGL path — the Vulkan path inherits the window default.
+            // Setting the format here, before SDL attaches its SurfaceView, ensures the
+            // SurfaceView is born with RGBA8888 and eliminates the format-change teardown
+            // (SurfaceHolder.SetFormat in DecorView.Post) that otherwise fires mid-Vulkan-init
+            // and can produce the "Draw thread did not acknowledge teardown within 250ms" warning.
+            // The DecorView.Post call and the SurfaceChanged reactive guard are retained as
+            // belt-and-braces fallbacks for timing windows or OEM variants where this hint is
+            // not honoured by the SurfaceView allocation path.
+            if (LogManagement.IsVulkanConfigured())
+            {
+                try
+                {
+                    Window?.SetFormat(global::Android.Graphics.Format.Rgba8888);
+                }
+                catch (Exception e)
+                {
+                    Debug.WriteLine($"[osu!] Pre-SDL Window.SetFormat(RGBA8888) failed (non-fatal): {e.Message}");
+                }
+            }
+
             base.OnCreate(savedInstanceState);
 
             // Wrap Platform.Init defensively: MAUI Essentials pulls in workload-version-sensitive
@@ -660,6 +683,13 @@ public void SurfaceChanged(ISurfaceHolder holder, global::Android.Graphics.Forma
             // picks up the new ANativeWindow and negotiates a proper BGRA/RGBA 8-bit swapchain.
             if (format == global::Android.Graphics.Format.Rgb565 && LogManagement.IsVulkanConfigured())
             {
+                Logger.Log(
+                    "[osu!] Android surface pixel format RGB565 detected mid-session (Vulkan path). " +
+                    "Requesting RGBA8888 and triggering a surface recreate. " +
+                    "If this fires after startup it indicates an OEM display-mode change " +
+                    "(e.g. SetSustainedPerformanceMode) reset the surface format.",
+                    LoggingTarget.Runtime,
+                    LogLevel.Important);
                 Logger.Log(
                     "[osu!] Android surface pixel format RGB565 is incompatible with the Vulkan rendering pipeline " +
                     "— requesting RGBA8888 and triggering a surface recreate. " +

osu.Android/OsuGameAndroid.cs

@@ -379,7 +379,7 @@ protected override void LoadComplete()
             //
             // Pinning Update + Draw + Input to a 5-core subset (mask 0xF8 on SD8G2) is the
             // ONLY unconditional Android-specific synchronous mutation we still perform
-            // during the cold-start window — every other customisation (SustainedPerformanceMode,
+            // during the cold-start window — every other customisation (
             // RequestUnbufferedDispatch, refresh-rate selection, Oboe / Vulkan-probe init,
             // performance-mode GC-latency flip) is already deferred behind the
             // refreshRateDelayMs scheduler below. Field logs.zip on v2026.423.176 show both
@@ -569,21 +569,28 @@ protected override void LoadComplete()
                 Debug.WriteLine($"[osu!] TameBackgroundThreads (initial) failed: {e.Message}");
             }
 
-            // Sustained performance mode is applied LATER, together with the deferred
-            // display-mode / GC-latency work below. See the Scheduler.AddDelayed block
-            // further down (after base.LoadComplete()) that schedules the first apply
-            // on a refreshRateDelayMs timer. Running
-            // Window.SetSustainedPerformanceMode(true) synchronously here — during the
-            // Toolbar cold-start texture-upload burst and the Vulkan swapchain bring-up —
-            // has been observed to race the Draw thread on Samsung One UI / Adreno panels:
-            // the window-flag mutation round-trips through ViewRootImpl.setPrivateFlags
-            // and can partially reconfigure the Surface while vkAcquireNextImageKHR is in
-            // flight, stalling the present queue. Update keeps ticking (so neither the
-            // managed nor the native watchdog ever dumps), the screen never updates, and
-            // ~10 s later Android raises a MotionEvent input-dispatch ANR — the exact
-            // cold-start "black screen → no touch → ANR" fingerprint reported across
-            // multiple v174 launches in logs.zip. Deferring to the same window used by
-            // SelectHighestRefreshRate moves the mutation behind the texture-upload burst.
+            // Window.SetSustainedPerformanceMode is intentionally NOT called anywhere.
+            //
+            // On Samsung One UI / Adreno devices, calling SetSustainedPerformanceMode(true)
+            // triggers a non-seamless display-mode transition (even when deferred behind the
+            // texture-upload burst). The transition momentarily destroys the SurfaceView,
+            // which resets the surface pixel format back to the Android default (RGB565 on
+            // high-density Samsung panels). Our SurfaceChanged reactive guard then calls
+            // SurfaceHolder.SetFormat(RGBA8888), causing a second surface-destroy/recreate
+            // cycle. During this second cycle the ANativeWindow transiently reports the
+            // display's scaled (dp) dimensions — 1029×480 on a 3088×1440 3×-density panel —
+            // instead of the physical pixel dimensions. Veldrid reads those dimensions from
+            // vkGetPhysicalDeviceSurfaceCapabilitiesKHR during its VkSurfaceKHR-loss
+            // recovery, creates a permanent swapchain at 1029×480, and SurfaceFlinger tiles
+            // that sub-screen image 3×3 to fill the display. The result is the "9 screens"
+            // artifact, blurry/flashing textures, and a sustained FPS drop observed on
+            // Galaxy S24 Ultra (Adreno 740, One UI 7, Android 15) with Vulkan enabled.
+            //
+            // Removing the call eliminates the mid-session surface teardown. ADPF performance
+            // hinting is already provided by Oboe's setPerformanceHintEnabled(true) (set
+            // during stream open in oboe_bridge.cpp), and GC low-latency is handled by
+            // AndroidHighPerformanceSessionManager (SustainedLowLatency GCSettings) which
+            // covers the same thermal/responsiveness goals without touching the Surface.
 
             base.LoadComplete();
 
@@ -688,27 +695,6 @@ protected override void LoadComplete()
                     Debug.WriteLine($"[osu!] Deferred SelectHighestRefreshRate failed: {ex.Message}");
                 }
 
-                // Deferred sustained-performance-mode apply. See the comment block
-                // before base.LoadComplete() above for the rationale (Samsung One UI /
-                // Adreno Surface reconfigure race with vkAcquireNextImageKHR during the
-                // cold-start texture-upload burst). By the time this fires the
-                // swapchain has long since stabilised.
-                try
-                {
-                    gameActivity.RunOnUiThread(() =>
-                    {
-                        try { gameActivity.Window?.SetSustainedPerformanceMode(true); }
-                        catch (Exception e)
-                        {
-                            Debug.WriteLine($"[osu!] Failed to enable sustained performance mode: {e.Message}");
-                        }
-                    });
-                }
-                catch (Exception e)
-                {
-                    Debug.WriteLine($"[osu!] Failed to dispatch sustained performance mode toggle to UI thread: {e.Message}");
-                }
-
                 // Deferred initial application of the user's performance-mode setting.
                 // The BindValueChanged registration below is WITHOUT the immediate-fire
                 // flag, so the very first apply (which may flip GCSettings.LatencyMode
@@ -1033,7 +1019,7 @@ protected override void LoadComplete()
             // the BDL load thread, in the silent cold-start window — exactly
             // when we are debugging a startup hang. Deferring the initial
             // fire via Scheduler.AddDelayed onto the same refreshRateDelayMs
-            // timer that gates SustainedPerformanceMode / the initial refresh-
+            // timer that gates the initial refresh-
             // rate apply / the initial performance-mode apply keeps the cold-
             // start path free of synchronous native init even when a saved-
             // true setting would otherwise force it, AND ensures the native
@@ -1149,8 +1135,9 @@ private void applyPerformanceOptimizations(bool enabled)
             {
                 try
                 {
-                    // Sustained performance mode is always on (set in LoadComplete).
                     // The performance toggle controls the high-perf GC session only.
+                    // (Window.SetSustainedPerformanceMode is intentionally not called —
+                    // see the comment before base.LoadComplete() for the full rationale.)
                     if (enabled)
                     {
                         highPerformanceSession ??= highPerformanceSessionManager.BeginSession();