linux-kernel - Re: [PATCH 8/8] cpufreq: vexpress: Use auto-registration for energy model

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Date:   Tue, 10 Aug 2021 11:11:31 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Vincent Donnefort <vincent.donnefort@....com>,
        Sudeep Holla <sudeep.holla@....com>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 8/8] cpufreq: vexpress: Use auto-registration for energy
 model



On 8/10/21 11:06 AM, Viresh Kumar wrote:
> On 10-08-21, 11:05, Lukasz Luba wrote:
>> I can see that this driver calls explicitly the
>> of_cpufreq_cooling_register()
>> It does this in the cpufreq_driver->ready() callback
>> implementation: ve_spc_cpufreq_ready()
>>
>> With that in mind, the new code in the patch 1/8, which
>> registers the EM, should be called even earlier, above:
>> ---------------------8<---------------------------------
>> /* Callback for handling stuff after policy is ready */
>> 	if (cpufreq_driver->ready)
>> 		cpufreq_driver->ready(policy);
>> ------------------->8----------------------------------
> 
> Thanks. I will look at this sequencing issue again.
> 
>> This also triggered a question:
>> If this new flag can be set in the cpufreq driver which hasn't set
>> CPUFREQ_IS_COOLING_DEV
>> ?
> 
> Why not ?

I thought someone could try to call cpufreq_cooling_register()
from the cpufreq driver init function, but it's not possible. I have
just checked that, so should be good with these two flags being
independent and working fine.

> 
>> I can only see one driver (this one in the patch) which has such
>> configuration.
>