From 6a845fd03bdfcf3435f7da840e6af1be6b74fee3 Mon Sep 17 00:00:00 2001
From: Zephyron <zephyron@citron-emu.org>
Date: Wed, 16 Apr 2025 19:28:15 +1000
Subject: [PATCH] feat: add option to respect present interval 0 as unlocked
 FPS

When enabled, this feature allows games using present interval 0 to run with
truly unlocked FPS, matching actual hardware behavior more accurately.

Previously, Citron would cap present interval 0 at 120FPS to conserve battery,
but this prevented proper functionality of dynamic framerate mods like UltraCam
by MaxLastBreath (https://www.nxoptimizer.com/).

The setting is disabled by default to maintain the current behavior for most users.

Signed-off-by: Zephyron <zephyron@citron-emu.org>
---
 src/common/settings.h                                 |  2 ++
 src/core/hle/service/nvnflinger/hardware_composer.cpp | 10 ++++++++++
 src/yuzu/configuration/shared_translation.cpp         |  6 ++++++
 3 files changed, 18 insertions(+)

diff --git a/src/common/settings.h b/src/common/settings.h
index d66f0279e9..ae90eda837 100644
--- a/src/common/settings.h
+++ b/src/common/settings.h
@@ -286,6 +286,8 @@ struct Values {
                                                                      Category::Renderer};
     SwitchableSetting<bool> use_asynchronous_gpu_emulation{
         linkage, true, "use_asynchronous_gpu_emulation", Category::Renderer};
+    SwitchableSetting<bool> respect_present_interval_zero{
+        linkage, false, "respect_present_interval_zero", Category::Renderer};
     SwitchableSetting<AstcDecodeMode, true> accelerate_astc{linkage,
 #ifdef ANDROID
                                                             AstcDecodeMode::Cpu,
diff --git a/src/core/hle/service/nvnflinger/hardware_composer.cpp b/src/core/hle/service/nvnflinger/hardware_composer.cpp
index 2433f5017e..a3cdad71f8 100644
--- a/src/core/hle/service/nvnflinger/hardware_composer.cpp
+++ b/src/core/hle/service/nvnflinger/hardware_composer.cpp
@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2024 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 citron Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include <boost/container/small_vector.hpp>
@@ -6,6 +7,7 @@
 
 #include "common/common_types.h"
 #include "common/microprofile.h"
+#include "common/settings.h"
 #include "core/hle/service/nvdrv/devices/nvdisp_disp0.h"
 #include "core/hle/service/nvnflinger/buffer_item.h"
 #include "core/hle/service/nvnflinger/buffer_item_consumer.h"
@@ -19,6 +21,14 @@ namespace {
 
 s32 NormalizeSwapInterval(f32* out_speed_scale, s32 swap_interval) {
     if (swap_interval <= 0) {
+        // If swap_interval is 0 and setting enabled, respect it as unlocked FPS
+        if (swap_interval == 0 && Settings::values.respect_present_interval_zero.GetValue()) {
+            if (out_speed_scale) {
+                *out_speed_scale = 1.0f;
+            }
+            return 0;
+        }
+
         // As an extension, treat nonpositive swap interval as speed multiplier.
         if (out_speed_scale) {
             *out_speed_scale = 2.f * static_cast<f32>(1 - swap_interval);
diff --git a/src/yuzu/configuration/shared_translation.cpp b/src/yuzu/configuration/shared_translation.cpp
index a4fcd818d2..cc7ffd9135 100644
--- a/src/yuzu/configuration/shared_translation.cpp
+++ b/src/yuzu/configuration/shared_translation.cpp
@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 citron Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "yuzu/configuration/shared_translation.h"
@@ -155,6 +156,11 @@ std::unique_ptr<TranslationMap> InitializeTranslations(QWidget* parent) {
     INSERT(
         Settings, use_asynchronous_gpu_emulation, tr("Use asynchronous GPU emulation"),
         tr("Uses an extra CPU thread for rendering.\nThis option should always remain enabled."));
+    INSERT(
+        Settings, respect_present_interval_zero, tr("Respect present interval 0 for unlocked FPS"),
+        tr("When enabled, present interval 0 will be used for games requesting unlocked FPS.\n"
+           "This matches console behavior more closely, but may cause higher battery usage and frame pacing issues.\n"
+           "When disabled (default), present interval 0 is capped at 120FPS to conserve battery."));
     INSERT(Settings, nvdec_emulation, tr("NVDEC emulation:"),
            tr("Specifies how videos should be decoded.\nIt can either use the CPU or the GPU for "
               "decoding, or perform no decoding at all (black screen on videos).\n"