linux-kernel - RE: [PATCH] of: thermal: Fixed governor at each thermal zone

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Date:   Wed, 28 Sep 2016 16:13:36 +0900
From:   강인혁/책임연구원/SW Platform(연)AOT팀(hugh.kang@....com) <hugh.kang@....com>
To:     Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Lukasz Luba <lukasz.luba@....com>
CC:     강인혁/책임연구원/SW Platform(연)AOT팀(hugh.kang@....com) <hugh.kang@....com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        정찬균/수석연구원/SW Platform(연)AOT팀(chan.jeong@....com) (chan.jeong@....com) <chan.jeong@....com>
Subject: RE: [PATCH] of: thermal: Fixed governor at each thermal zone

Hello Rui, Javi, Lukasz and Eduardo

> -----Original Message-----
> From: Zhang Rui [mailto:rui.zhang@...el.com]
> Sent: Wednesday, September 28, 2016 10:31 AM
> To: Eduardo Valentin; Lukasz Luba
> Cc: Inhyuk Kang; linux-pm@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH] of: thermal: Fixed governor at each thermal zone
> 
> Hi, Javi, Lukasz and Eduardo,
> 
> thanks for your input.
> 
> thanks,
> rui
> 
> On 二, 2016-09-27 at 06:22 -0700, Eduardo Valentin wrote:
> > Hello, Lukasz, Inhyuk, Javi,
> >
> > On Tue, Sep 27, 2016 at 12:52:04PM +0100, Lukasz Luba wrote:
> > >
> > >
> > > On 27/09/16 02:46, Zhang Rui wrote:
> > > >
> > > > On 一, 2016-09-19 at 10:18 +0900, Inhyuk Kang wrote:
> > > > >
> > > > > It is necessary to be added governor at each thermal_zone.
> > > > > Because some governors should be operated in the during the
> > > > > kernel booting in order to avoid heating problem.
> > > > >
> > > > > Default governor cannot be covered all thermal zones policy
> > > > > because some thermal zones want to apply different one.
> > > > > For example, the power allocator governor operates differently
> > > > > with step wise governor.
> > > > > Hence, it is better to parse governor parameter from the device
> > > > > tree.
> > > > >
> > > > > Signed-off-by: Inhyuk Kang <hugh.kang@....com>
> > > > >
> > > > The patch looks okay to me.
> > > > Eduardo, what do you think of this patch?
> > > Hi Rui,
> > >
> > > Beside the fact which Javi pointed out in his email, there is an
> > > issue in the patch itself.
> > > The idea behind the patch is good, but the patch should have some
> > > improvements, i.e:
> > > - strncpy instead of strcpy,
> > > - if the governor name is not found in the registered governor's
> > > list by __find_governor (and then null is set) we should probably
> > > switch to default governor,
> > > - add DT documentation,
> > Also, the idea of the patch is good, almost tempting to do it, but
> > unfortunately, not acceptable from DT perspective. The patch infringes
> > two of the DT conceptual and design decision of:
> > (a) DT should describe hardware, not policy;
> > (b) DT should describe hardware, not OS specific implementations.
> >
> > As already pointed by Javi, this patch has already been proposed (more
> > than one time by different people), but, it still continues to be
> > unacceptable.
> >
> > Cheers,
> >
> >
> > >
> > >
> > > Regards,
> > > Lukasz
> > >
Thank you for reviewing this patch. I understand your ideas. 
During the thermal testing into device, the thermal policy should be applied in the begging of kernel boot sometimes.
Hence, I have suggested above solution.

Anyway, the DT perspective like above, this patch is better not to be upstream.

Thank you very much.

Regards,
Hugh Kang

No One ever is defeated until defeat has been accepted as a reality.
강인혁 (Hugh Kang) Chief Engineer
SW Platform(연) Advanced OS Technology TEAM (AOT)
Mobile: +82-10-5513-7957