[PATCH] arm: dts: mt7623: increase passive cooling trip

[Kurt Fitzner]

This issue and patch just came to my attention, my apologies for late 
comments.

The solution provided in this patch is, I believe, not optimal.

On 2021-07-25 1:34 p.m., Frank Wunderlich wrote:
> From: Frank Wunderlich <frank-w at public-files.de>
> 
> MT7623/BPI-R2 has idle temperature after bootup from 48 degrees celsius
> increase the passive trip temp threshold to not trottle CPU frequency at
> this temperature

The dts file for the mt7623 has four trip points:
- Trip point 0, Type=Passive @ 47°C (originally, now 57°C)
- Trip point 1, Type=Active @ 67°C
- Trip point 2, Type=Hot @ 87°C
- Trip point 3, Type=Critical @ 107°C

It makes little sense to have passive CPU throttling employed *before* 
engaging a fan.  Generally users want a fan (if present) to be engaged 
before intentional performance degradation is employed.

>   					cpu_passive: cpu-passive {
> -						temperature = <47000>;
> +						temperature = <57000>;

The old temperature of 47°C appears, in practice, to be a good 
temperature for an active cooling trip point.  It is just above the 
temperature that a generally idle mt7623 sits at in enclosures where 
this SoC is employed, but also a temperature that a CPU under load will 
quickly reach.

Therefore I propose the types of trip points 0 and 1 be reversed and the 
temperatures left as they were.


--- a/arch/arm/boot/dts/mt7623.dtsi	2022-02-27 18:36:33 -0400
+++ b/arch/arm/boot/dts/mt7623.dtsi	2022-03-05 11:37:52 -0400
@@ -158,19 +158,19 @@

  				thermal-sensors = <&thermal 0>;

  				trips {
  					cpu_passive: cpu-passive {
-						temperature = <57000>;
+						temperature = <47000>;
  						hysteresis = <2000>;
-						type = "passive";
+						type = "active";
  					};

  					cpu_active: cpu-active {
  						temperature = <67000>;
  						hysteresis = <2000>;
-						type = "active";
+						type = "passive";
  					};

  					cpu_hot: cpu-hot {
  						temperature = <87000>;
  						hysteresis = <2000>;