VRR flicker mitigations

src/Backends/DRMBackend.cpp

@@ -4020,19 +4020,26 @@ namespace gamescope
 			if ( bDefer && !!( g_uCompositeDebug & CompositeDebugFlag::Markers ) )
 				g_uCompositeDebug |= CompositeDebugFlag::Markers_Partial;
 
-			std::optional oCompositeResult = vulkan_composite( &compositeFrameInfo, nullptr, !bNeedsFullComposite );
+			// Only present composites advance the output ring, so the last one is still on screen.
+			const bool bReuseLastComposite = pFrameInfo->bRepeatFrame && bNeedsFullComposite &&
+				m_bWasCompositing && !m_bWasPartialCompositing && vulkan_get_last_output_image( false, false ) != nullptr;
 
-			m_bWasCompositing = true;
+			if ( !bReuseLastComposite )
+			{
+				std::optional oCompositeResult = vulkan_composite( &compositeFrameInfo, nullptr, !bNeedsFullComposite );
 
-			g_uCompositeDebug &= ~CompositeDebugFlag::Markers_Partial;
+				m_bWasCompositing = true;
 
-			if ( !oCompositeResult )
-			{
-				xwm_log.errorf("vulkan_composite failed");
-				return -EINVAL;
-			}
+				g_uCompositeDebug &= ~CompositeDebugFlag::Markers_Partial;
 
-			vulkan_wait( *oCompositeResult, true );
+				if ( !oCompositeResult )
+				{
+					xwm_log.errorf("vulkan_composite failed");
+					return -EINVAL;
+				}
+
+				vulkan_wait( *oCompositeResult, true );
+			}
 
 			FrameInfo_t presentCompFrameInfo = {};
 			presentCompFrameInfo.allowVRR = pFrameInfo->allowVRR;

src/rendervulkan.cpp

@@ -4681,6 +4681,10 @@ bool vulkan_format_supports_features(VkFormat format, VkFormatFeatureFlags featu
 
 gamescope::Rc<CVulkanTexture> vulkan_get_last_output_image( bool partial, bool defer )
 {
+	// A remake drops the deferred images until the next composite makes them.
+	if ( g_output.outputImages.empty() )
+		return nullptr;
+
 	// Get previous image ( +2 )
 	// 1 2 3
 	//   |

src/rendervulkan.hpp

@@ -301,6 +301,8 @@ struct FrameInfo_t
 	gamescope::Rc<CVulkanTexture> lut3D[EOTF_Count];
 
 	bool allowVRR;
+	// Content identical to the previous present, eg. an adaptive sync idle hold.
+	bool bRepeatFrame;
 	bool applyOutputColorMgmt; // drm only
 	EOTF outputEncodingEOTF;
 

src/steamcompmgr.cpp

@@ -301,6 +301,8 @@ gamescope::ConVar<bool> cv_adaptive_sync( "adaptive_sync", false, "Whether or no
 gamescope::ConVar<bool> cv_adaptive_sync_ignore_overlay( "adaptive_sync_ignore_overlay", false, "Whether or not to ignore overlay planes for pushing commits with adaptive sync." );
 gamescope::ConVar<int> cv_adaptive_sync_overlay_cycles( "adaptive_sync_overlay_cycles", 1, "Number of vblank cycles to ignore overlay repaints before forcing a commit with adaptive sync." );
 gamescope::ConVar<bool> cv_adaptive_sync_uncapped( "adaptive_sync_uncapped", true, "Whether or not to allow mailbox/immediate clients to run uncapped with adaptive sync by deferring paints until the display can take a new flip." );
+gamescope::ConVar<int> cv_adaptive_sync_cursor_min_fps( "adaptive_sync_cursor_min_fps", 30, "Content frame rate at or above which cursor repaints coalesce with content frames when adaptive sync is on. 0 = repaint the cursor immediately." );
+gamescope::ConVar<bool> cv_adaptive_sync_idle_hold( "adaptive_sync_idle_hold", true, "Hold the display at its refresh rate while the Steam UI is focused with adaptive sync." );
 
 gamescope::ConVar<bool> cv_upscale_preemptive( "upscale_preemptive", true, "Allow pre-emptive upscaling" );
 gamescope::ConVar<bool> cv_upscale_preemptive_debug_force_sync( "upscale_preemptive_debug_force_sync", false, "Force synchronize pre-emptive upscaling" );
@@ -1115,6 +1117,7 @@ uint32_t		lastPublishedInputCounter;
 
 std::atomic<bool> hasRepaint = false;
 bool			hasRepaintNonBasePlane = false;
+std::atomic<bool> hasCursorRepaint = false;
 
 bool			g_bUpdateForwardedVROverlays = false;
 
@@ -2058,7 +2061,7 @@ void MouseCursor::checkSuspension()
 
 			// We're hiding the cursor, force redraw if we were showing it
 			if (window && !m_imageEmpty ) {
-				hasRepaintNonBasePlane = true;
+				hasCursorRepaint = true;
 				nudge_steamcompmgr();
 			}
 		}
@@ -3096,7 +3099,7 @@ gamescope::ConVar<bool> cv_paint_cursor_plane{ "paint_cursor_plane", true };
 gamescope::ConVar<bool> cv_paint_mura_plane{ "paint_mura_plane", true };
 
 static void
-paint_all( global_focus_t *pFocus, bool async )
+paint_all( global_focus_t *pFocus, bool async, bool bRepeatFrame )
 {
 	if ( !pFocus )
 		return;
@@ -3110,8 +3113,13 @@ paint_all( global_focus_t *pFocus, bool async )
 
 	static long long int paintID = 0;
 
+	const uint32_t uColorMgmtSerial = g_ColorMgmt.serial;
 	update_color_mgmt();
 
+	// New LUTs need a fresh composite even when nothing was damaged.
+	if ( g_ColorMgmt.serial != uColorMgmtSerial )
+		bRepeatFrame = false;
+
 	paintID++;
 	gpuvis_trace_begin_ctx_printf( paintID, "paint_all" );
 	steamcompmgr_win_t	*w;
@@ -3156,6 +3164,7 @@ paint_all( global_focus_t *pFocus, bool async )
 	frameInfo.applyOutputColorMgmt = g_ColorMgmt.pending.enabled;
 	frameInfo.outputEncodingEOTF = g_ColorMgmt.pending.outputEncodingEOTF;
 	frameInfo.allowVRR = cv_adaptive_sync;
+	frameInfo.bRepeatFrame = bRepeatFrame;
 	frameInfo.bFadingOut = fadingOut;
 	frameInfo.eUpscaleFilter = pFocus->eUpscaleFilter;
 	frameInfo.eUpscaleScaler = pFocus->eUpscaleScaler;
@@ -10735,6 +10744,7 @@ steamcompmgr_main(int argc, char **argv)
 		bool bPainted = false;
 
 		static int nIgnoredOverlayRepaints = 0;
+		static uint64_t s_ulLastContentPaintTime = 0;
 
 		if ( !hasRepaintNonBasePlane )
 			nIgnoredOverlayRepaints = 0;
@@ -10745,6 +10755,7 @@ steamcompmgr_main(int argc, char **argv)
 		for ( auto &iter : g_VirtualConnectorFocuses )
 		{
 			global_focus_t *pPaintFocus = &iter.second;
+			bool bRepeatFrame = false;
 
 			const UpscaleSettings_t upscaleSettings = GetUpscaleSettings(
 				window_is_steam( pPaintFocus->focusWindow ),
@@ -10835,13 +10846,13 @@ steamcompmgr_main(int argc, char **argv)
 				{
 					case FlipType::Normal:
 					{
-						bShouldPaint = vblank && ( hasRepaint || hasRepaintNonBasePlane || bForceSyncFlip );
+						bShouldPaint = vblank && ( hasRepaint || hasRepaintNonBasePlane || hasCursorRepaint || bForceSyncFlip );
 						break;
 					}
 
 					case FlipType::Async:
 					{
-						bShouldPaint = hasRepaint;
+						bShouldPaint = hasRepaint || hasCursorRepaint;
 
 						if ( vblank && !bShouldPaint && hasRepaintNonBasePlane )
 							nIgnoredOverlayRepaints++;
@@ -10853,6 +10864,25 @@ steamcompmgr_main(int argc, char **argv)
 					{
 						bShouldPaint = hasRepaint && bVRRCanFlip;
 
+						// Content at or above adaptive_sync_cursor_min_fps carries the cursor with its own frames.
+						if ( !bShouldPaint && hasCursorRepaint && bVRRCanFlip )
+						{
+							const int nCursorMinFPS = cv_adaptive_sync_cursor_min_fps;
+							if ( nCursorMinFPS <= 0 ||
+							     get_time_in_nanos() - s_ulLastContentPaintTime >= 1'000'000'000ul / uint64_t( nCursorMinFPS ) )
+							{
+								bShouldPaint = true;
+							}
+						}
+
+						// Hold the Steam UI at the refresh rate so an idle panel can't stretch toward its minimum and flicker.
+						if ( !bShouldPaint && bIsVBlankFromTimer && g_bSteamIsActiveWindow &&
+						     cv_adaptive_sync_idle_hold )
+						{
+							bShouldPaint = true;
+							bRepeatFrame = !hasCursorRepaint && !hasRepaintNonBasePlane;
+						}
+
 						if ( bIsVBlankFromTimer )
 						{
 							if ( hasRepaintNonBasePlane )
@@ -10890,7 +10920,7 @@ steamcompmgr_main(int argc, char **argv)
 
 			if ( bShouldPaint )
 			{
-				paint_all( pPaintFocus, eFlipType == FlipType::Async );
+				paint_all( pPaintFocus, eFlipType == FlipType::Async, bRepeatFrame );
 
 				bPainted = true;
 			}
@@ -10909,8 +10939,12 @@ steamcompmgr_main(int argc, char **argv)
 		{
 			GetBackend()->OnEndFrame();
 
+			if ( hasRepaint )
+				s_ulLastContentPaintTime = get_time_in_nanos();
+
 			hasRepaint = false;
 			hasRepaintNonBasePlane = false;
+			hasCursorRepaint = false;
 			nIgnoredOverlayRepaints = 0;
 
 			{

src/wlserver.cpp

@@ -118,6 +118,7 @@ struct wlr_surface *wlserver_surface_to_main_surface( struct wlr_surface *pSurfa
 bool wlserver_process_hotkeys( wlr_keyboard *keyboard, uint32_t key, bool press );
 
 extern std::atomic<bool> hasRepaint;
+extern std::atomic<bool> hasCursorRepaint;
 
 std::vector<ResListEntry_t>& gamescope_xwayland_server_t::retrieve_commits()
 {
@@ -2818,7 +2819,7 @@ void wlserver_oncursorevent()
 
 	if ( !wlserver.bCursorHidden && wlserver.bCursorHasImage )
 	{
-		hasRepaint = true;
+		hasCursorRepaint = true;
 	}
 }
 
@@ -2972,7 +2973,7 @@ void wlserver_mousehide()
 	if ( wlserver.bCursorHidden != true )
 	{
 		wlserver.bCursorHidden = true;
-		hasRepaint = true;
+		hasCursorRepaint = true;
 	}
 }