Hi,

Gesendet: Donnerstag, 24. Juni 2021 um 15:29 Uhr
Von: "Eric Woudstra" [off-list ref]
The SOC runs unthrotlled slowly to 80 degrees. This takes minutes. Polling interval 1 second or less does not matter much when looking at these temperature rise times 

After that in more then an hour it slowly creeps up to 85. I believe the design is so that the SOC, under normal circumstances, can run at 1.35 GHz without throttling frequency, without heatsink. It just needs a safeguard for different circumstances.

Most of these SOCs can also run in industrial grade circumstances, which means up to 85 degrees ambient temperature already . If not industrial then this would be 60 degrees ambient already 

But only someone at Mediatek can confirm this 

maybe Matthias knows anybody?
get_maintainers-script shows no mtk employee for mtk_thermal driver, added Sean and Ryder as common Linux-Contacts...

Daniel from openwrt have some other mt7622 Boards maybe he can test the Fan approach below

On Jun 24, 2021, 12:21 PM, at 12:21 PM, Daniel Lezcano [off-list ref] wrote:

quoted

Found that:

https://download.kamami.pl/p579344-MT7622A_Datasheet_for_BananaPi_Only%281%29.pdf

Chapter 3.3 - Thermal Characteristics

Given the values I suggest:

- Passive - 80°C

- Hot - 90°C

- Critical - 100°C

maybe adding FAN (r64, don't know for other mt7622 boards) for lower 2 trips (with adjusted temperature points) and cpu-throtteling for upper 2 trips

something like this (used the 70/80 trip points discussed before):

--- a/arch/arm64/boot/dts/mediatek/mt7622.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt7622.dtsi

@@ -134,6 +134,13 @@
 		};
 	};
 
+	fan0: pwm-fan {
+		compatible = "pwm-fan";
+		#cooling-cells = <2>;
+		pwms = <&pwm 2 10000 0>;
+		cooling-levels = <0 102 170 230>;
+	};
+
 	thermal-zones {
 		cpu_thermal: cpu-thermal {
 			polling-delay-passive = <1000>;

@@ -143,13 +150,13 @@
 
 			trips {
 				cpu_passive: cpu-passive {
-					temperature = <47000>;
+					temperature = <70000>;
 					hysteresis = <2000>;
 					type = "passive";
 				};
 
 				cpu_active: cpu-active {
-					temperature = <67000>;
+					temperature = <80000>;
 					hysteresis = <2000>;
 					type = "active";
 				};

@@ -170,14 +177,12 @@
 			cooling-maps {
 				map0 {
 					trip = <&cpu_passive>;
-					cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
-							 <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+					cooling-device = <&fan0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
 				};
 
 				map1 {
 					trip = <&cpu_active>;
-					cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
-							 <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+					cooling-device = <&fan0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
 				};
 
 				map2 {

@@ -428,6 +433,7 @@
 	pwm: pwm@11006000 {
 		compatible = "mediatek,mt7622-pwm";
 		reg = <0 0x11006000 0 0x1000>;
+		#pwm-cells = <3>;
 		interrupts = <GIC_SPI 77 IRQ_TYPE_LEVEL_LOW>;
 		clocks = <&topckgen CLK_TOP_PWM_SEL>,
 			 <&pericfg CLK_PERI_PWM_PD>,

regards Frank