linux-kernel - Re: [PATCH v6 03/10] PM / EM: update callback structure and add device pointer

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Date:   Thu, 23 Apr 2020 16:28:18 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org, linux-omap@...r.kernel.org,
        linux-mediatek@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
        linux-imx@....com, Dietmar.Eggemann@....com, cw00.choi@...sung.com,
        b.zolnierkie@...sung.com, rjw@...ysocki.net, sudeep.holla@....com,
        viresh.kumar@...aro.org, nm@...com, sboyd@...nel.org,
        rui.zhang@...el.com, amit.kucheria@...durent.com, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, rostedt@...dmis.org,
        qperret@...gle.com, bsegall@...gle.com, mgorman@...e.de,
        shawnguo@...nel.org, s.hauer@...gutronix.de, festevam@...il.com,
        kernel@...gutronix.de, khilman@...nel.org, agross@...nel.org,
        bjorn.andersson@...aro.org, robh@...nel.org,
        matthias.bgg@...il.com, steven.price@....com,
        tomeu.vizoso@...labora.com, alyssa.rosenzweig@...labora.com,
        airlied@...ux.ie, daniel@...ll.ch, liviu.dudau@....com,
        lorenzo.pieralisi@....com, patrick.bellasi@...bug.net,
        orjan.eide@....com, rdunlap@...radead.org, mka@...omium.org
Subject: Re: [PATCH v6 03/10] PM / EM: update callback structure and add
 device pointer

Hi Daniel,

On 4/23/20 2:22 PM, Daniel Lezcano wrote:
> On Fri, Apr 10, 2020 at 09:42:03AM +0100, Lukasz Luba wrote:
>> The Energy Model framework is going to support devices other that CPUs. In
>> order to make this happen change the callback function and add pointer to
>> a device as an argument.
>>
>> Update the related users to use new function and new callback from the
>> Energy Model.
>>
>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
>> ---
> 
> [ ... ]
> 
>> +static struct em_perf_domain *
>> +em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb,
>> +	     cpumask_t *span)
>>   {
>>   	unsigned long opp_eff, prev_opp_eff = ULONG_MAX;
>>   	unsigned long power, freq, prev_freq = 0;
>> @@ -106,7 +107,7 @@ static struct em_perf_domain *em_create_pd(cpumask_t *span, int nr_states,
>>   		 * lowest performance state of 'cpu' above 'freq' and updates
>>   		 * 'power' and 'freq' accordingly.
>>   		 */
>> -		ret = cb->active_power(&power, &freq, cpu);
>> +		ret = cb->active_power(&power, &freq, dev);
>>   		if (ret) {
>>   			pr_err("pd%d: invalid perf. state: %d\n", cpu, ret);
>>   			goto free_ps_table;
> 
> Why are the changes 'cpu' to 'dev' in the patch 4/10 instead of this one ?

The patch 4/10 is quite big and I didn't want to put also this change in
there. I thought for readability it would be better to have a separate
patch with self-contained change (or I got your suggestion too strict).

In this patch I just wanted to show more precisely that this function
callback 'active_power' which is used by 2 users (currently):
cpufreq/scmi-cpufreq.c and opp/of.c
is going to change an argument and these files are affected.

The 4/10 changes a lot lines, while first 3 patches can be treated as
a preparation for the upcoming major change (4/10).

Thank you for the review.

Regards,
Lukasz

> 
>> @@ -237,7 +238,7 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
>>   	}
>>   
>>   	/* Create the performance domain and add it to the Energy Model. */
>> -	pd = em_create_pd(span, nr_states, cb);
>> +	pd = em_create_pd(dev, nr_states, cb, span);
>>   	if (!pd) {
>>   		ret = -EINVAL;
>>   		goto unlock;
>