MIUI Display Refresh Rate Locker

Overview

MIUI Display Refresh Rate Locker (developed by key, based on research by kevmck, Liangmisanxing, and kakathic) is a targeted optimization module designed to fix the aggressive refresh rate drops prevalent on Xiaomi MIUI and HyperOS firmware.

While Xiaomi smartphones offer smooth 120Hz and 144Hz OLED displays, the stock system regularly throttles refresh rates to 60Hz when playing videos, reading ebooks, or opening third-party tools. This constant frequency fluctuation causes visible micro-stutter when scrolling or switching apps. This module completely stabilizes screen refresh rate.

Technical Architecture & How It Works

The module neutralizes MIUI’s frequency throttling across multiple system properties via system.prop:

1. SurfaceFlinger Property Overrides

# Disable dynamic smart fps adaptation
persist.sys.smartfps=0

# Disable vendor default fps downclocking switch
ro.vendor.fps.switch.default=false

# Disable content-aware refresh rate scaling in SurfaceFlinger
ro.surface_flinger.use_content_detection_for_refresh_rate=false

2. Framework Daemon Harmonization

By instructing the Android SurfaceFlinger compositor to ignore video playback frame-rate metadata, the display controller maintains the maximum scan rate regardless of whether the foreground media is 24 FPS, 30 FPS, or 60 FPS.

Troubleshooting & Verification

• Real-Time Frequency Display: Navigate to Settings > Additional settings > Developer options and enable Show refresh rate to verify the persistent 120Hz/144Hz lock.
• Battery Temperature: Under extreme ambient temperatures, the device kernel may engage thermal safety throttles; this is a kernel-level hardware protection distinct from software SmartFPS.