From f464205af021c13c98376a57b3a4e68f8791d950 Mon Sep 17 00:00:00 2001
From: IanSB <isb@clara.co.uk>
Date: Fri, 26 Nov 2021 11:40:11 +0000
Subject: [PATCH] Dont overclock core on Pi4 unless >100Mhz

---
 src/defs.h | 6 +-----
 src/info.c | 6 +++++-
 src/osd.c  | 8 ++++++++
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/defs.h b/src/defs.h
index 68190371..0cb8a5eb 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -8,10 +8,6 @@
 #define _RPI3 3
 #define _RPI4 4
 
-#ifdef RPI4
-//#define RPI4D
-#endif
-
 #ifdef USE_ARM_CAPTURE
 #ifdef RPI4
 #define USE_ALT_M7DEINTERLACE_CODE           // uses re-ordered code for mode7 deinterlace
@@ -484,7 +480,7 @@ typedef struct {
 #if defined(RPI4)
 #define SCALER_DISPLAY_LIST (volatile uint32_t *)(_get_peripheral_base() + 0x404000)
 #else
-#define SCALER_DISPLAY_LIST (volatile uint32_t *)(_get_peripheral_base() + 0x402000)    
+#define SCALER_DISPLAY_LIST (volatile uint32_t *)(_get_peripheral_base() + 0x402000)
 #endif
 
 #define PIXEL_FORMAT 1  // RGBA4444
diff --git a/src/info.c b/src/info.c
index 4b86c959..214b31a6 100644
--- a/src/info.c
+++ b/src/info.c
@@ -59,7 +59,7 @@ unsigned int get_clock_rate(int clk_id) {
 
 void set_clock_rates(unsigned int cpu, unsigned int core, unsigned int sdram) {
 static unsigned int old_core = -1;
-static unsigned int old_cpu = -1;  
+static unsigned int old_cpu = -1;
    if (core != old_core) {
        delay_in_arm_cycles_cpu_adjust(50000000);
    }
@@ -68,11 +68,15 @@ static unsigned int old_cpu = -1;
    RPI_PropertyAddTag(TAG_SET_CLOCK_RATE, CORE_CLK_ID, core, 0);
    RPI_PropertyAddTag(TAG_SET_CLOCK_RATE, SDRAM_CLK_ID, sdram, 0);
    RPI_PropertyProcess();
+
    if (core != old_core) {
+#ifndef RPI4
        RPI_AuxMiniUartFlush();
        RPI_AuxMiniUartInit(115200, 8);
+#endif
        old_core = core;
    }
+
    if (cpu != old_cpu) {
        calculate_cpu_timings();
        old_cpu = cpu;
diff --git a/src/osd.c b/src/osd.c
index 11f3cd30..fe183b45 100644
--- a/src/osd.c
+++ b/src/osd.c
@@ -1222,7 +1222,15 @@ static void set_clocks(){
             auto_core = 150;     //overclock to 400
         }
     }
+#ifdef RPI4
+    if (core_overclock > 100) {  //pi 4 core is already 500 Mhz (all others 400Mhz) so don't overclock unless overclock >100Mhz
+        set_clock_rates((cpu_clock + auto_cpu + cpu_overclock) * 1000000, (core_clock + auto_core + core_overclock - 100) * 1000000, (sdram_clock + sdram_overclock) * 1000000);
+    } else {
+        set_clock_rates((cpu_clock + auto_cpu + cpu_overclock) * 1000000, (core_clock + auto_core) * 1000000, (sdram_clock + sdram_overclock) * 1000000);
+    }
+#else
     set_clock_rates((cpu_clock + auto_cpu + cpu_overclock) * 1000000, (core_clock + auto_core + core_overclock) * 1000000, (sdram_clock + sdram_overclock) * 1000000);
+#endif
 }
 
 static void set_feature(int num, int value) {