linux-kernel - Re: [PATCH v3 4/6] arm64: Enable dynamic CPU capacity initialization

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Message-ID: <56B89B05.4090207@arm.com>
Date:	Mon, 8 Feb 2016 13:41:25 +0000
From:	Dietmar Eggemann <dietmar.eggemann@....com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Juri Lelli <juri.lelli@....com>, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org, peterz@...radead.org,
	vincent.guittot@...aro.org, robh+dt@...nel.org,
	mark.rutland@....com, linux@....linux.org.uk, sudeep.holla@....com,
	lorenzo.pieralisi@....com, catalin.marinas@....com,
	will.deacon@....com, morten.rasmussen@....com
Subject: Re: [PATCH v3 4/6] arm64: Enable dynamic CPU capacity initialization

On 08/02/16 13:13, Mark Brown wrote:
> On Mon, Feb 08, 2016 at 12:28:39PM +0000, Dietmar Eggemann wrote:
>> On 03/02/16 11:59, Juri Lelli wrote:
> 
>>> +bool arch_wants_init_cpu_capacity(void)
>>> +{
>>> +	return true;
> 
>> Isn't this a little bit too simple? Not every ARM/ARM64 platform is a
>> heterogeneous one.
> 
> Does it matter?  Is there any problem with doing the callibration and
> having it say that all the CPUs performs very similarly?  My
> understanding was that this was simply saying it was worth checking to
> see if there was some asymmetry.
> 

No, the calibration would work on any platform. I can see your point,
you want to have this feature not depend on dt.