Thread (19 messages) 19 messages, 4 authors, 2021-06-25

Re: Aw: Re: Re: Re: [PATCH] Fix mt7622.dtsi thermal cpu

From: Daniel Lezcano <hidden>
Date: 2021-06-25 12:50:48
Also in: linux-arm-kernel, linux-mediatek, lkml

On 25/06/2021 14:28, Frank Wunderlich wrote:
quoted
Gesendet: Freitag, 25. Juni 2021 um 13:47 Uhr
Von: "Daniel Lezcano" [off-list ref]
quoted
quoted
but we need to disable the passive trip as cpu-trotteling starts there...the higher temperature trips are currently not reached
Sorry, can you rephrase it ? I'm not getting the point.
the problem currently is that passive is at 47degress Celsius and
trottles cpu, active (67°C) and hot points are never reached this way.
so at least we need to change temperatures in dtsi, and maybe disable
cpu-trotteling on passive trip. imho fan will never start if it is in
active and cpu is trottled before in passive
Ok, thanks for the clarification.
quoted
quoted
summary

moving fan and cpu_thermal-override to bananapi-r64.dts

passive-trip: cooling-device = <&cpu0/1 0 0> as in erics Patch
active trip: cooling-device = <&fan0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
the other 2 unchanged

but i suggest changing the temperature points in mt7622 dtsi as this is SoC specific

so basicly:
--- a/arch/arm64/boot/dts/mediatek/mt7622.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
@@ -143,13 +143,13 @@ cpu_thermal: cpu-thermal {

                        trips {
                                cpu_passive: cpu-passive {
-                                       temperature = <47000>;
+                                       temperature = <70000>;
May be increase the passive temp to 75°C.
quoted
                                        hysteresis = <2000>;
                                        type = "passive";
                                };

                                cpu_active: cpu-active {
-                                       temperature = <67000>;
+                                       temperature = <80000>;
                                        hysteresis = <2000>;
                                        type = "active";
                                };
Move the active trip 'cpu_active' to mt7622-bananapi-bpi-r64.dts. and
set it to 70°C in the mt7622-bananapi-bpi-r64.dts, so the fan will act
before the cpu throttling.

The behavior should be the following: The temperature reaches 70°C, the
fan will start, if the temperature continues to increase, it will
increase the speed. If the temperature reaches 75°C, the fan is still
rotating at full speed but the cpu begins to be throttled.
passive to 75 and active lower to 70? is this as intended that active comes before passive?
Yes. So there is a default passive mitigation temp for the SoC at 75°C.
And the bpi has a setup with a fan mitigating before the cpu throttling.
mt7622-bananapi-bpi-r64.dts:

&cpu_thermal {
	trips {
		cpu_passive: cpu-passive {
			temperature = <75000>;
			hysteresis = <2000>;
			type = "passive";
		};
No need to add this trip point, it should be changed to 75°C in SoC DT
mt7622.dtsi. This fragment of DT will concatenate with the previous one.
		cpu_active: cpu-active {
			temperature = <70000>;
			hysteresis = <2000>;
			type = "active";
		};
	};

	cooling-maps {
		map1 {
			trip = <&cpu_active>;
			cooling-device = <&fan0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
		};
	};
};

quoted
AFAIU, it is a Cortex-A53 running @1.35GH, so except the board is in a
black metal box under the sun, I don't see how we can reach this thermal
limits.
quoted
@@ -170,8 +170,8 @@ cpu-crit {
                        cooling-maps {
                                map0 {
                                        trip = <&cpu_passive>;
-                                       cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
-                                                        <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+                                       cooling-device = <&cpu0 0 0>,
+                                                        <&cpu1 0 0>;
You should keep it untouched.
then cpu is trottled at passive point (currently 47°C) and imho fan does not start at active
quoted
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                                };

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