linux-kernel - Re: [RESEND][PATCH 7/8] thermal: cooling: Check Energy Model type in cpufreq_cooling and devfreq

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Date:   Tue, 29 Mar 2022 07:37:08 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linux-kernel@...r.kernel.org, dietmar.eggemann@....com,
        Pierre.Gondois@....com, ionela.voinescu@....com, rafael@...nel.org,
        daniel.lezcano@...aro.org, linux-pm@...r.kernel.org,
        mka@...omium.org, nm@...com, sboyd@...nel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, cristian.marussi@....com,
        sudeep.holla@....com, matthias.bgg@...il.com
Subject: Re: [RESEND][PATCH 7/8] thermal: cooling: Check Energy Model type in
 cpufreq_cooling and devfreq_cooling



On 3/28/22 04:27, Viresh Kumar wrote:
> On 21-03-22, 09:57, Lukasz Luba wrote:
>> The Energy Model can now be artificial, which means the power values
>> are mathematically generated to leverage EAS while not expected to be on
>> an uniform scale with other devices providing power information. If this
>> EM type is in use, the thermal governor IPA should not be allowed to
>> operate, since the relation between cooling devices is not properly
>> defined. Thus, it might be possible that big GPU has lower power values
>> than a Little CPU. To mitigate a misbehaviour of the thermal control
>> algorithm, simply do not register the cooling device as IPA's power
>> actor.
>>
>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
>> ---
>>   drivers/thermal/cpufreq_cooling.c | 2 +-
>>   drivers/thermal/devfreq_cooling.c | 8 +++++---
>>   2 files changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
>> index 0bfb8eebd126..b8151d95a806 100644
>> --- a/drivers/thermal/cpufreq_cooling.c
>> +++ b/drivers/thermal/cpufreq_cooling.c
>> @@ -328,7 +328,7 @@ static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
>>   	struct cpufreq_policy *policy;
>>   	unsigned int nr_levels;
>>   
>> -	if (!em)
>> +	if (!em || em_is_artificial(em))
>>   		return false;
>>   
>>   	policy = cpufreq_cdev->policy;
>> diff --git a/drivers/thermal/devfreq_cooling.c b/drivers/thermal/devfreq_cooling.c
>> index 4310cb342a9f..b04dcbbf721a 100644
>> --- a/drivers/thermal/devfreq_cooling.c
>> +++ b/drivers/thermal/devfreq_cooling.c
>> @@ -358,6 +358,7 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
>>   	struct thermal_cooling_device *cdev;
>>   	struct device *dev = df->dev.parent;
>>   	struct devfreq_cooling_device *dfc;
>> +	struct em_perf_domain *em;
>>   	char *name;
>>   	int err, num_opps;
>>   
>> @@ -367,8 +368,9 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
>>   
>>   	dfc->devfreq = df;
>>   
>> -	dfc->em_pd = em_pd_get(dev);
>> -	if (dfc->em_pd) {
>> +	em = em_pd_get(dev);
>> +	if (em && !em_is_artificial(em)) {
>> +		dfc->em_pd = em;
>>   		devfreq_cooling_ops.get_requested_power =
>>   			devfreq_cooling_get_requested_power;
>>   		devfreq_cooling_ops.state2power = devfreq_cooling_state2power;
>> @@ -379,7 +381,7 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
>>   		num_opps = em_pd_nr_perf_states(dfc->em_pd);
>>   	} else {
>>   		/* Backward compatibility for drivers which do not use IPA */
>> -		dev_dbg(dev, "missing EM for cooling device\n");
>> +		dev_dbg(dev, "missing proper EM for cooling device\n");
>>   
>>   		num_opps = dev_pm_opp_get_opp_count(dev);
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> 

Thank you Viresh for the ACK!