[PATCH 3/3] cpufreq: exynos: Add exynos5420 cpufreq driver

[Lukasz Majewski]

Hi Viresh,

> On 6 December 2013 15:18, Arun Kumar K <arun.kk at samsung.com> wrote:
> > From: "Arjun.K.V" <arjun.kv at samsung.com>
> >
> > The patch adds cpufreq driver for exynos5420.
> >
> > Signed-off-by: Arjun.K.V <arjun.kv at samsung.com>
> > Signed-off-by: Andrew Bresticker <abrestic at chromium.org>
> > Signed-off-by: Arun Kumar K <arun.kk at samsung.com>
> > ---
> >  drivers/cpufreq/Kconfig.arm          |   11 ++
> >  drivers/cpufreq/Makefile             |    1 +
> >  drivers/cpufreq/exynos-cpufreq.c     |    2 +
> >  drivers/cpufreq/exynos-cpufreq.h     |    8 +
> >  drivers/cpufreq/exynos5420-cpufreq.c |  346
> > ++++++++++++++++++++++++++++++++++ 5 files changed, 368
> > insertions(+) create mode 100644
> > drivers/cpufreq/exynos5420-cpufreq.c
> 
> Hmm.. That's the second big LITTLE SoC after TC2..
> And we already have a generic enough driver for all big LITTLE
> platforms: arm_big_little.c
> 
> Please use that with a glue clk and regulator driver if required. We
> don't want to get any new driver for big LITTLE unless there is a
> real limitation.
> 
> Also, the generic big LITTLE driver supports IKS (In Kernel Switcher)
> which may or maynot be used by Exynos.
> 
> @Lukasz: We can't use cpu0 driver here as we have multiple clusters
> here A7 and A15, and so there are two clock domains instead of one.
> That's why we have written big LITTLE driver.

When I first looked into the patch - it was almost identical to the
exynos4210-cpufreq.c or exynos4x12-cpufreq.c files.

Also I didn't spot the code characteristic to IKS. It seems like the
code in this file is not aware if it runs on A7 or A15.

That was the rationale on proposing reusing cpufreq-cpu0 code (which I
plan to use as a replacement for current exynos4xxx-cpufreq code).

> 
> @Arun: And you logs must be a bit enhanced as well.. I knew 5420 is
> big LITTLE but others may not.. And hence please provide a summary of
> your platform whenever you add new drivers..
> 
> --
> viresh
> 
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-- 
Best regards,

Lukasz Majewski

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