linux-kernel - Re: [PATCH v4 4/5] cpufreq: qcom-cpufreq-hw: Use new thermal pressure update function

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Date:   Tue, 16 Nov 2021 08:28:53 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, steev@...i.org,
        sudeep.holla@....com, will@...nel.org, catalin.marinas@....com,
        linux@...linux.org.uk, gregkh@...uxfoundation.org,
        rafael@...nel.org, viresh.kumar@...aro.org, amitk@...nel.org,
        daniel.lezcano@...aro.org, amit.kachhap@...il.com,
        bjorn.andersson@...aro.org, agross@...nel.org
Subject: Re: [PATCH v4 4/5] cpufreq: qcom-cpufreq-hw: Use new thermal pressure
 update function

Hi Thara,

On 11/15/21 11:39 PM, Thara Gopinath wrote:
> 
> 
> On 11/15/21 3:57 PM, Thara Gopinath wrote:
>>
>>
>> On 11/9/21 2:57 PM, Lukasz Luba wrote:
>>> Thermal pressure provides a new API, which allows to use CPU frequency
>>> as an argument. That removes the need of local conversion to capacity.
>>> Use this new API and remove old local conversion code.
>>>
>>> The new arch_update_thermal_pressure() also accepts boost frequencies,
>>> which solves issue in the driver code with wrong reduced capacity
>>> calculation. The reduced capacity was calculated wrongly due to
>>> 'policy->cpuinfo.max_freq' used as a divider. The value present there 
>>> was
>>> actually the boost frequency. Thus, even a normal maximum frequency 
>>> value
>>> which corresponds to max CPU capacity (arch_scale_cpu_capacity(cpu_id))
>>> is not able to remove the capping.
> 
> Also I failed to mention that, currently freq_factor is initialized as 
> cpuinfo.max_freq / 1000 which means again all the issues you mentioned 
> below can be hit, if some cpufreq driver decides to set boost at init.
> I have sent a patch earlier today to fix this.

Yes, you are right.

> 
> https://lore.kernel.org/linux-arm-msm/20211115201010.68567-1-thara.gopinath@linaro.org/T/#u 
> 
> 

Looking at the change, it makes sense. I'll try to respond to that
patch.

Thank you for looking into this issue.

Regards,
Lukasz