linux-kernel - Re: [PATCH v3 6/7] thermal/drivers/cpu_cooling: Introduce the cpu idle cooling driver

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Message-ID: <20180416122911.GC3706@e107533-lin>
Date:   Mon, 16 Apr 2018 13:29:11 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>, edubezval@...il.com,
        kevin.wangtao@...aro.org, leo.yan@...aro.org,
        vincent.guittot@...aro.org, linux-kernel@...r.kernel.org,
        javi.merino@...nel.org, rui.zhang@...el.com,
        daniel.thompson@...aro.org, linux-pm@...r.kernel.org,
        Amit Daniel Kachhap <amit.kachhap@...il.com>
Subject: Re: [PATCH v3 6/7] thermal/drivers/cpu_cooling: Introduce the cpu
 idle cooling driver

On Mon, Apr 16, 2018 at 03:20:06PM +0530, Viresh Kumar wrote:
> On 16-04-18, 11:45, Daniel Lezcano wrote:
> > Can you elaborate a bit ? I'm not sure to get the point.
> 
> Sure. With your current code on Hikey960 (big/LITTLE), you end up
> creating two cooling devices, one for the big cluster and one for
> small cluster. Which is the right thing to do, as we also have two
> cpufreq cooling devices.
> 
> But with the change Sudeep is referring to, the helper you used to get
> cluster id will return 0 (SoC id) for all the 8 CPUs. So your code
> will end up creating a single cpuidle cooling device for all the CPUs.
> Which would be wrong.
> 
> > BTW, Am I asked to change my code to stick to something which is not
> > merged ?
> 
> Sudeep looked pretty confident on how the meaning of this routine is
> going to change very soon. I will let him respond on what guarantees
> we have that it will get merged :)
> 

Viresh has already summarised it correctly. I don't have much to add.
Unless the system has multiple package, this routine will return 0(or some
fixed socket number, I don't think it can be different from 0 but
theoretically it can be anything but has to be same for all the CPUs)

--
Regards,
Sudeep