linux-kernel - Re: [PATCH v3 4/5] cpufreq: qcom-cpufreq-hw: Use new thermal pressure update function

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Date:   Fri, 5 Nov 2021 15:12:00 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Lukasz Luba <lukasz.luba@....com>, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.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 v3 4/5] cpufreq: qcom-cpufreq-hw: Use new thermal pressure
 update function

Hi Lukasz,


On 11/3/21 12:10 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.
> 
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
>   drivers/cpufreq/qcom-cpufreq-hw.c | 15 +++++----------
>   1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index 0138b2ec406d..425f351450ad 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -275,10 +275,10 @@ static unsigned int qcom_lmh_get_throttle_freq(struct qcom_cpufreq_data *data)
>   
>   static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data)
>   {
> -	unsigned long max_capacity, capacity, freq_hz, throttled_freq;
>   	struct cpufreq_policy *policy = data->policy;
>   	int cpu = cpumask_first(policy->cpus);
>   	struct device *dev = get_cpu_device(cpu);
> +	unsigned long freq_hz, throttled_freq;
>   	struct dev_pm_opp *opp;
>   	unsigned int freq;
>   
> @@ -295,17 +295,12 @@ static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data)
>   
>   	throttled_freq = freq_hz / HZ_PER_KHZ;
>   
> -	/* Update thermal pressure */
> -
> -	max_capacity = arch_scale_cpu_capacity(cpu);
> -	capacity = mult_frac(max_capacity, throttled_freq, policy->cpuinfo.max_freq);
> -
>   	/* Don't pass boost capacity to scheduler */
> -	if (capacity > max_capacity)
> -		capacity = max_capacity;

So, I think this should go into the common 
topology_update_thermal_pressure in lieu of

+	if (WARN_ON(max_freq < capped_freq))
+		return;

This will fix the issue Steev Klimaszewski has been reporting
https://lore.kernel.org/linux-arm-kernel/3cba148a-7077-7b6b-f131-dc65045aa348@arm.com/


-- 
Warm Regards
Thara (She/Her/Hers)


> +	if (throttled_freq > policy->cpuinfo.max_freq)
> +		throttled_freq = policy->cpuinfo.max_freq;
>   
> -	arch_set_thermal_pressure(policy->related_cpus,
> -				  max_capacity - capacity);
> +	/* Update thermal pressure */
> +	arch_update_thermal_pressure(policy->related_cpus, throttled_freq);
>   
>   	/*
>   	 * In the unlikely case policy is unregistered do not enable
>