linux-kernel - Re: [PATCH 2/2] arm64: dts: qcom: sm7225-fairphone-fp4: Add PM6150L thermals

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Date: Wed, 10 Jan 2024 20:16:57 +0100
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: Luca Weiss <luca.weiss@...rphone.com>,
 Bjorn Andersson <andersson@...nel.org>, Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>
Cc: ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH 2/2] arm64: dts: qcom: sm7225-fairphone-fp4: Add PM6150L
 thermals



On 1/9/24 12:24, Luca Weiss wrote:
> On Tue Jan 9, 2024 at 11:09 AM CET, Konrad Dybcio wrote:
>>
>>
>> On 1/5/24 15:54, Luca Weiss wrote:
>>> Configure the thermals for the PA_THERM1, MSM_THERM, PA_THERM0,
>>> RFC_CAM_THERM, CAM_FLASH_THERM and QUIET_THERM thermistors connected to
>>> PM6150L.
>>>
>>> Due to hardware constraints we can only register 4 zones with
>>> pm6150l_adc_tm, the other 2 we can register via generic-adc-thermal.
>>
>> Ugh.. so the ADC can support more inputs than the ADC_TM that was
>> designed to ship alongside it can?
>>
>> And that's why the "generic-adc-thermal"-provided zones need to
>> be polled?
> 
> This part of the code from qcom-spmi-adc-tm5.c was trigerring if I
> define more than 4 channels, and looking at downstream I can also see
> that only 4 zones are registered properly with adc_tm, the rest is
> registered with "qcom,adc-tm5-iio" which skips from what I could tell
> basically all the HW bits and only registering the thermal zone.
> 
> 
> 	ret = adc_tm5_read(chip, ADC_TM5_NUM_BTM,
> 			   &channels_available, sizeof(channels_available));
> 	if (ret) {
> 		dev_err(chip->dev, "read failed for BTM channels\n");
> 		return ret;
> 	}
> 
> 	for (i = 0; i < chip->nchannels; i++) {
> 		if (chip->channels[i].channel >= channels_available) {
> 			dev_err(chip->dev, "Invalid channel %d\n", chip->channels[i].channel);
> 			return -EINVAL;
> 		}
> 	}
> 
> 
>>
>>>
>>> The trip points can really only be considered as placeholders, more
>>> configuration with cooling etc. can be added later.
>>>
>>> Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
>>> ---
>> [...]
>>
>> I've read the sentence above, but..
>>> +		sdm-skin-thermal {
>>> +			polling-delay-passive = <1000>;
>>> +			polling-delay = <5000>;
>>> +			thermal-sensors = <&msm_therm_sensor>;
>>> +
>>> +			trips {
>>> +				active-config0 {
>>> +					temperature = <125000>;
>>> +					hysteresis = <1000>;
>>> +					type = "passive";
>>
>> I don't fancy burnt fingers for dinner!
> 
> With passive trip point it wouldn't even do anything now, but at what
> temp do you think it should do what? I'd definitely need more time to
> understand more of how the thermal setup works in downstream Android,
> and then replicate a sane configuration for mainline with proper
> temperatures, cooling, etc.
If "skin therm" means "the temperature of some part of the phone's
body that can be felt with a human hand", then definitely some
throttling should happen at 40ish with heavy throttling at 50
and crit at 55 or so..

We should probably make this a broader topic and keep a single
policy for all supported phones.

+ CC AGdR, may be interested in where this leads

Konrad