[nvmflinger] fixed 30fps cap for games with swap_interval=2, and prefer newest queued frames to reduce input latency

src/core/hle/service/nvnflinger/buffer_queue_consumer.cpp

@@ -45,6 +45,17 @@ Status BufferQueueConsumer::AcquireBuffer(BufferItem* out_buffer,
 
     auto front(core->queue.begin());
 
+    // prefer newest queued frame for lower input latency (if no present deadline is requested).
+    if (expected_present.count() == 0 && core->queue.size() > 1) {
+        while (core->queue.size() > 1) {
+            const auto stale = core->queue.begin();
+            if (core->StillTracking(*stale)) slots[stale->slot].buffer_state = BufferState::Free;
+            core->queue.erase(stale);
+        }
+        core->SignalDequeueCondition();
+        front = core->queue.begin();
+    }
+
     // If expected_present is specified, we may not want to return a buffer yet.
     if (expected_present.count() != 0) {
         constexpr auto MAX_REASONABLE_NSEC = 1000000000LL; // 1 second

src/core/hle/service/nvnflinger/hardware_composer.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 2024 yuzu Emulator Project
@@ -77,26 +77,7 @@ u32 HardwareComposer::ComposeLocked(f32* out_speed_scale, Display& display,
     // Acquire all necessary framebuffers.
     for (auto& layer : display.stack.layers) {
         auto consumer_id = layer->consumer_id;
-
-        bool should_try_acquire = true;
-        if (!layer->is_overlay) {
-            auto fb_it = m_framebuffers.find(consumer_id);
-            if (fb_it != m_framebuffers.end() && fb_it->second.is_acquired) {
-                const u64 frames_since_last_acquire = m_frame_number - fb_it->second.last_acquire_frame;
-                const s32 expected_interval = NormalizeSwapInterval(nullptr, fb_it->second.item.swap_interval);
-
-                if (frames_since_last_acquire < static_cast<u64>(expected_interval)) {
-                    should_try_acquire = false;
-                }
-            }
-        }
-
-        // Try to fetch the framebuffer (either new or stale).
-        const auto result = should_try_acquire
-            ? this->CacheFramebufferLocked(*layer, consumer_id)
-            : (m_framebuffers.find(consumer_id) != m_framebuffers.end() && m_framebuffers[consumer_id].is_acquired
-                ? CacheStatus::CachedBufferReused
-                : CacheStatus::NoBufferAvailable);
+        const auto result = this->CacheFramebufferLocked(*layer, consumer_id);
 
         // If we failed, skip this layer.
         if (result == CacheStatus::NoBufferAvailable) {
@@ -134,9 +115,9 @@ u32 HardwareComposer::ComposeLocked(f32* out_speed_scale, Display& display,
             continue;
         }
 
-        // We need to compose again either before this frame is supposed to
-        // be released, or exactly on the vsync period it should be released.
-        const s32 item_swap_interval = NormalizeSwapInterval(out_speed_scale, item.swap_interval);
+        // hard-throttle non-overlay presentation cadence on 1..4 removed!!
+        NormalizeSwapInterval(out_speed_scale, item.swap_interval);
+        const s32 item_swap_interval = 1;
 
         // TODO: handle cases where swap intervals are relatively prime. So far,
         // only swap intervals of 0, 1 and 2 have been observed, but if 3 were
@@ -233,9 +214,8 @@ bool HardwareComposer::TryAcquireFramebufferLocked(Layer& layer, Framebuffer& fr
         return false;
     }
 
-    // We succeeded, so set the new release frame info.
-    const s32 swap_interval = layer.is_overlay ? 1 : NormalizeSwapInterval(nullptr, framebuffer.item.swap_interval);
-    framebuffer.release_frame_number = m_frame_number + swap_interval;
+    // Keep 60Hz consumer cadence and let producer queue timing decide effective FPS.
+    framebuffer.release_frame_number = m_frame_number + 1;
     framebuffer.last_acquire_frame = m_frame_number;
     framebuffer.is_acquired = true;