Re: [PATCH v2 0/4] Apple SoC cpufreq driver

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Hector Martin <marcan@marcan.st>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Sven Peter <sven@svenpeter.dev>,
	Alyssa Rosenzweig <alyssa@rosenzweig.io>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Marc Zyngier <maz@kernel.org>,
	Mark Kettenis <mark.kettenis@xs4all.nl>,
	linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/4] Apple SoC cpufreq driver
Date: Wed, 4 May 2022 21:30:19 +0530	[thread overview]
Message-ID: <20220504160019.GB3507@thinkpad> (raw)
In-Reply-To: <20220504102745.fv5bl2cphq7ft4lm@vireshk-i7>

Hi Viresh,

On Wed, May 04, 2022 at 03:57:45PM +0530, Viresh Kumar wrote:
> On 04-05-22, 16:51, Hector Martin wrote:
> > Hi folks,
> > 
> > Here's a second take on the cpufreq driver for Apple SoCs. This is a
> > complete rewrite using a stand-alone cpufreq driver instead of using the
> > cpufreq-dt infrastructure.
> > 
> > Since v1 we ran some experiments on the memory controller performance
> > switching and it turns out it doesn't make a huge difference, so it
> > makes sense to punt that feature to the future (perhaps once a proper
> > memory controller driver exists for other reasons, e.g. for error
> > handling).
> > 
> > One advantage of having a standalone cpufreq driver is that we can
> > support fast switching. This also means any future interaction with
> > the memory controller will probably use some bespoke mechanism instead
> > of the genpd infrastructure, so we can keep the fast path without
> > allowing sleeps/etc.
> > 
> > The driver is based on scpi-cpufreq.c, with some bits (e.g. the
> > apple,freq-domain stuff) inspired by how cpufreq-qcom-hw does it.
> > I'm not sure if that particular property should be described
> > in a binding, since it goes in the cpu nodes (qcom doesn't have it
> > anywhere...).
> 
> Hi Mani,
> 
> I can see that Rob asked you to add this somewhere, maybe in arm/cpu
> stuff, but I don't think you ever sent a patch with that. What
> happened ?
> 
> https://lore.kernel.org/lkml/20201013171800.GA3716411@bogus/
> 

Oops. Looks like that one slipped through the cracks. I did add it to my todo
list for qcom-cpufreq but missed it completely.

I will look into it.

Thanks,
Mani

> -- 
> viresh