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

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Date:   Wed, 11 Jan 2017 19:40:54 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Alex Shi <alex.shi@...aro.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        open list <linux-kernel@...r.kernel.org>,
        Linux PM <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

On Wed, Jan 11, 2017 at 3:33 PM, Alex Shi <alex.shi@...aro.org> wrote:
>
>>> >  #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. :)

But instead of putting the #ifdef into the function body, you can use
a wrapper function defined to be empty for CONFIG_PM unset.

Thanks,
Rafael