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

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Message-ID: <67107afb-6ed9-9681-6fce-0d52e567ea12@linaro.org>
Date:   Fri, 25 Jun 2021 14:50:42 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Frank Wunderlich <frank-w@...lic-files.de>
Cc:     Eric Woudstra <ericwouds@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sean Wang <sean.wang@...iatek.com>,
        Ryder Lee <ryder.lee@...iatek.com>,
        Daniel Golle <daniel@...rotopia.org>
Subject: Re: Aw: Re: Re: Re: [PATCH] Fix mt7622.dtsi thermal cpu

On 25/06/2021 14:28, Frank Wunderlich wrote:
>> Gesendet: Freitag, 25. Juni 2021 um 13:47 Uhr
>> Von: "Daniel Lezcano" <daniel.lezcano@...aro.org>
> 
>>> 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.

>>> 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.
>>
>>>                                         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>;
> 		};
> 	};
> };
> 
> 
>> 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.
>>
>>> @@ -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
> 
>>>                                 };
> 


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