linux-kernel - Re: [PATCH 2/3] cpu: expose pm_qos_resume

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Date:   Wed, 11 Jan 2017 22:33:56 +0800
From:   Alex Shi <alex.shi@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        vincent.guittot@...aro.org,
        open list <linux-kernel@...r.kernel.org>,
        linux-pm@...r.kernel.org, Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH 2/3] cpu: expose pm_qos_resume_latency for each cpu

>> >  #include "base.h"
>> >  
>> > @@ -376,6 +377,9 @@ int register_cpu(struct cpu *cpu, int num)
>> >  
>> >  	per_cpu(cpu_sys_devices, num) = &cpu->dev;
>> >  	register_cpu_under_node(num, cpu_to_node(num));
>> > +#ifdef CONFIG_CPU_IDLE_GOV_MENU
>> > +	dev_pm_qos_expose_latency_limit(&cpu->dev, 0);
>> > +#endif
> No way to do this without the #ifdef?  That's really not recommended for
> .c code :(
> 

Hi Greg,

Thanks for comments!

The function dev_pm_qos_expose_latency_limit() is null if no CONFIG_PM.
So when CONFIG_PM enabled, may we could consider the cpu idle is also
wanted. In this assumption the #ifdef could be removed. If user want to
use this feature, she/he should understand the feature only work on menu
gov only currently. So consider this, I guess we could remove this
#ifdef. :)

Any different concerns on this?

Regards
Alex

BTW,
Although I did try this patch on other platform, but it clearly other
multi core system, like x86 could also get the same benefit.