linux-kernel - Re: [PATCH 4/4] cpufreq: scmi: Support the power scale in micro-Watts in SCMI v3.1

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Message-ID: <95d76278-ce40-aab8-1418-322f8b4a3072@arm.com>
Date:   Wed, 6 Jul 2022 10:08:05 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     amitk@...nel.org, rui.zhang@...el.com, viresh.kumar@...aro.org,
        rafael@...nel.org, dietmar.eggemann@....com, nm@...com,
        sboyd@...nel.org, sudeep.holla@....com, cristian.marussi@....com,
        linux-kernel@...r.kernel.org, matthias.bgg@...il.com,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 4/4] cpufreq: scmi: Support the power scale in micro-Watts
 in SCMI v3.1



On 7/5/22 10:25, Daniel Lezcano wrote:
> On 22/06/2022 16:58, Lukasz Luba wrote:
>> The SCMI v3.1 adds support for power values in micro-Watts. They are not
>> always in milli-Watts anymore (ignoring the bogo-Watts). Thus, the power
>> must be converted conditionally before sending to Energy Model. Add the
>> logic which handles the needed checks and conversions.
>>
>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
>> ---
>>   drivers/cpufreq/scmi-cpufreq.c | 15 ++++++++++-----
>>   1 file changed, 10 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/cpufreq/scmi-cpufreq.c 
>> b/drivers/cpufreq/scmi-cpufreq.c
>> index bfd35583d653..513a071845c2 100644
>> --- a/drivers/cpufreq/scmi-cpufreq.c
>> +++ b/drivers/cpufreq/scmi-cpufreq.c
>> @@ -100,7 +100,7 @@ static int __maybe_unused
>>   scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
>>              unsigned long *KHz)
>>   {
>> -    bool power_scale_mw = perf_ops->power_scale_mw_get(ph);
>> +    enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
>>       unsigned long Hz;
>>       int ret, domain;
>> @@ -114,8 +114,8 @@ scmi_get_cpu_power(struct device *cpu_dev, 
>> unsigned long *power,
>>       if (ret)
>>           return ret;
>> -    /* Provide bigger resolution power to the Energy Model */
>> -    if (power_scale_mw)
>> +    /* Convert the power to uW if it is mW (ignore bogoW) */
>> +    if (power_scale == SCMI_POWER_MILLIWATTS)
>>           *power *= MICROWATT_PER_MILLIWATT;
>>       /* The EM framework specifies the frequency in KHz. */
>> @@ -255,8 +255,9 @@ static int scmi_cpufreq_exit(struct cpufreq_policy 
>> *policy)
>>   static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
>>   {
>>       struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
>> -    bool power_scale_mw = perf_ops->power_scale_mw_get(ph);
>> +    enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
>>       struct scmi_data *priv = policy->driver_data;
>> +    bool em_power_scale = false;
> 
> Just pass 'false' to em_dev_register_perf_domain()

We cannot,

> 
>>       /*
>>        * This callback will be called for each policy, but we don't 
>> need to
>> @@ -268,9 +269,13 @@ static void scmi_cpufreq_register_em(struct 
>> cpufreq_policy *policy)
>>       if (!priv->nr_opp)
>>           return;
>> +    if (power_scale == SCMI_POWER_MILLIWATTS
>> +        || power_scale == SCMI_POWER_MICROWATTS)
>> +        em_power_scale = true;
>> +

because sometimes it's 'true'.

>>       em_dev_register_perf_domain(get_cpu_device(policy->cpu), 
>> priv->nr_opp,
>>                       &em_cb, priv->opp_shared_cpus,
>> -                    power_scale_mw);
>> +                    em_power_scale);

Then we just use the variable here in single call.

>>   }
>>   static struct cpufreq_driver scmi_cpufreq_driver = {
> 
>