Re: [PATCH v9 4/6] ARM: Exynos: switch to using generic cpufreq driver for Exynos4210/5250/5420

From: Lukasz Majewski <l.majewski@samsung.com>
To: Tomasz Figa <tomasz.figa@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>,
	Kukjin Kim <kgene.kim@samsung.com>,
	mturquette@linaro.org, heiko@sntech.de, linux-pm@vger.kernel.org,
	viresh.kumar@linaro.org,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	amit.kucheria@linaro.org, cw00.choi@samsung.com,
	Thomas Abraham <thomas.ab@samsung.com>,
	linux-samsung-soc@vger.kernel.org,
	linaro-kernel@lists.linaro.org,
	linux-arm-kernel@lists.infradead.org,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Lukasz Majewski <l.majewski@majess.pl>
Subject: Re: [PATCH v9 4/6] ARM: Exynos: switch to using generic cpufreq driver for Exynos4210/5250/5420
Date: Mon, 25 Aug 2014 08:53:52 +0200	[thread overview]
Message-ID: <20140825085352.14290508@amdc2363> (raw)
In-Reply-To: <53F7DA13.6090305@gmail.com>

Hi Tomasz,

> Hi Kevin,
> 
> Thanks for taking a look at this.
> 
> On 23.08.2014 01:54, Kevin Hilman wrote:
> > Tomasz Figa <tomasz.figa@gmail.com> writes:
> > 
> >> Kukjin,
> >>
> >> On 31.07.2014 20:32, Kukjin Kim wrote:
> >>> On 07/30/14 17:07, Thomas Abraham wrote:
> >>>> The new CPU clock type allows the use of generic CPUfreq
> >>>> drivers. So for Exynos4210/5250, switch to using generic cpufreq
> >>>> driver. For Exynos5420, which did not have CPUfreq driver
> >>>> support, enable the use of generic CPUfreq driver.
> >>>>
> >>>> Suggested-by: Tomasz Figa<t.figa@samsung.com>
> >>>> Cc: Kukjin Kim<kgene.kim@samsung.com>
> >>>
> >>> Looks good to me,
> >>>
> >>> Acked-by: Kukjin Kim <kgene.kim@samsung.com>
> >>>
> >>> BTW, who will handle this series? I hope see this series in 3.17.
> >>
> >> This series consists mostly of clock changes and it likely depends
> >> on patches already in my for-next, so I would be inclined toward
> >> taking it through samsung-clk tree. 
> > 
> > So has this series been picked up anywhere?  I don't see it in your
> > samsung-clk tree, nor in Kukjin's for-next.
> 
> No, it has not. In general it was already too late in the release
> cycle when the last version was posted.
> 
> I had a plan to take it through clock tree with Kukjin's and Viresh's
> cooperation, but now as you say it...
> 
> > 
> > Also, I'm curious whether or how this is has been tested on
> > big.LITTLE SoCs.  
> > 
> > I'm trying it on the 5800/Chromebook2 and it's not terribly
> > stable.  I'm testing along with CPUidle, so there may be some
> > untested interactions there as it seems a bit more stable without
> > CPUidle enabled.
> > 
> > I'd love to hear from anyone else that's testing CPUidle and CPUfreq
> > together big.LITTLE 5420/5800, with or without the switcher.
> 
> I'd definitely like to see a clarification on this issues, before this
> series hits mainline or at least its parts related to affected SoCs.

It is a huge step forward - to be honest it is a serious rework of
cpufreq subsystem for Exynos SoCs.

> Also I'd like to hear some confirmation from Samsung Poland R&D Center
> guys (on CC), whether this code works stable on their target boards
> (Universal C210, Trats, Trats2).
> 

Since we have missed the merge window with this code, I can declare
that I will provide code, which means that I will do the cleanup for
excluded from this series Exynos4 SoCs, to test the cpufreq-cpu0.

However, I'm concerned with Exynos4412, which supports BOOST. It might
not be trivial to provide support for it.

I think, that we shall not drop behind any functionality during clean
up.

> > 
> > Also, the patch below[2] is needed for 5800.
> > 
> > FWIW, I have a temporary branch[1] based on the v3.17-rc branch of
> > the exynos-reference tree where I've added the DT patch needed for
> > CPUidle, this series (and it's dependencies) which is what I'm
> > using for testing.
> 
> The patch looks fine to me (well, it's trivial :)), thanks.
> 
> Best regards,
> Tomasz
> 
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-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group