linux-kernel - Re: [PATCH v4 2/3] PM / EM: Expose perf domain struct

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Message-ID: <cf1474cb-7e31-7070-b988-a0c4d3f6f081@linaro.org>
Date:   Wed, 15 May 2019 12:16:34 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Quentin Perret <quentin.perret@....com>
Cc:     edubezval@...il.com, rui.zhang@...el.com, javi.merino@...nel.org,
        viresh.kumar@...aro.org, amit.kachhap@...il.com, rjw@...ysocki.net,
        will.deacon@....com, catalin.marinas@....com,
        dietmar.eggemann@....com, ionela.voinescu@....com,
        mka@...omium.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 2/3] PM / EM: Expose perf domain struct

On 15/05/2019 12:07, Quentin Perret wrote:
> On Wednesday 15 May 2019 at 11:56:30 (+0200), Daniel Lezcano wrote:
>> On 15/05/2019 11:17, Quentin Perret wrote:
>>> Hi Daniel,
>>>
>>> On Wednesday 15 May 2019 at 11:06:18 (+0200), Daniel Lezcano wrote:
>>>> On 15/05/2019 10:23, Quentin Perret wrote:
>>>>> In the current state, the perf_domain struct is fully defined only when
>>>>> CONFIG_ENERGY_MODEL=y. Since we need to write code that compiles both
>>>>> with or without that option in the thermal framework, make sure to
>>>>> actually define the struct regardless of the config option. That allows
>>>>> to avoid using stubbed accessor functions all the time in code paths
>>>>> that use the EM.
>>>>>
>>>>> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
>>>>> Signed-off-by: Quentin Perret <quentin.perret@....com>
>>>>
>>>> This patch implies the cpu cooling device can be set without the energy
>>>> model.
>>>>
>>>> Isn't it possible to make a strong dependency for the cpu cooling device
>>>> on the energy model option, add the energy model as default on arm arch
>>>> and drop this patch?
>>>
>>> Right, that should work too.
>>>
>>>> After all, the cpu cooling is using the em framework.
>>>
>>> The reason I did it that way is simply to keep things flexible. If you
>>> don't compile in THERMAL_GOV_POWER_ALLOCATOR, you will never use the EM
>>> for CPU thermal. So I thought it would be good to not mandate compiling
>>> in ENERGY_MODEL in this case -- that should save a bit of space.
>>>
>>> But TBH I don't have a strong opinion on this one, so if everybody
>>> agrees it's fine to just make CPU_THERMAL depend on ENERGY_MODEL, I'm
>>> happy to drop this patch and fix patch 3/3. That would indeed simplify
>>> things a bit.
>>
>> Ok in this case it will be better to drop the 2/3 and add a small series
>> doing for the cpu_cooling.c
>>
>> #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
>>
>> /* structure freq */
>>
>> /* power2state */
>>
>> /* state2power*/
>>
>> /* getrequestedpower */
>>
>> /* All functions needed for the above */
>>
>> #endif
>>
>> static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
>>         .get_max_state          = cpufreq_get_max_state,
>>         .get_cur_state          = cpufreq_get_cur_state,
>>         .set_cur_state          = cpufreq_set_cur_state,
>> #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
>>         .get_requested_power    = cpufreq_get_requested_power,
>>         .state2power            = cpufreq_state2power,
>>         .power2state            = cpufreq_power2state,
>> #endif
>> };
>>
>> So you don't have to care about ENERGY_MODEL to be set as
>> THERMAL_GOV_POWER_ALLOCATOR depends on it.
>>
>> I think the result for cpu_cooling.c will be even more cleaner with the
>> em change.
> 
> OK, that works for me. I'll give it a go in v5.

Viresh what do you think ?


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