linux-kernel - RE: [PATCH v4 06/11] ARM: EXYNOS: Add support for mapping PMU base address via DT

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Message-id: <000401cf89f7$7db93190$792b94b0$@samsung.com>
Date:	Tue, 17 Jun 2014 12:13:45 +0530
From:	Pankaj Dubey <pankaj.dubey@...sung.com>
To:	'Tomasz Figa' <t.figa@...sung.com>,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc:	kgene.kim@...sung.com, linux@....linux.org.uk,
	chow.kim@...sung.com, vikas.sajjan@...sung.com, joshi@...sung.com
Subject: RE: [PATCH v4 06/11] ARM: EXYNOS: Add support for mapping PMU base
 address via DT

Hi Tomasz,

> Hi,
> 
> On 10.05.2014 08:56, Pankaj Dubey wrote:
> > From: Young-Gun Jang <yg1004.jang@...sung.com>
> >
> > Add support for mapping Samsung Power Management Unit (PMU) base
> > address from device tree. This patch also adds helper function as
> > "get_exynos_pmuregmap". This function can be used by other machine
> > files such as "pm.c", "hotplug.c" for accessing PMU regmap handle.
> >
> 
> I don't think there is a need to use regmap to provide access to PMU to
such low
> level code such as pm.c or hotplug.c. Moreover, I believe that it might be
undesirable
> in some cases, e.g. very low level code running at early resume or late
suspend.
> 
> IMHO, based on what we now have for SYSRAM, you could simply map PMU from
> device tree one time, before SMP init, and keep the address in some
globally
> accessible variable, like those for SYSRAM we have right now
(sysram_base_addr,
> sysram_ns_base_addr -> pmu_base_addr).
> 

Thanks for review. 

Well I adopted same approach in V1 of this patch series. 

V1: https://lkml.org/lkml/2014/4/2/48

So, if we do not have issues with that approach, I think we can map PMU
address
one time and use it for all machine files including pmu.c. 
Also I can see that early_syscon patch [1] is not progressing anymore,
so in next version of this series better I remove dependency of early syscon
and usage
of regmap.

1: https://lkml.org/lkml/2014/4/8/239

Tomasz, It will be good if you can review remaining patches under this
series, specially patch [2].
So that, I can update this series after addressing all comments.

2: https://lkml.org/lkml/2014/5/10/26


> Then, registration of the normal syscon would happen through standard
platform
> driver mechanisms and no special early handling would be necessary.
> 
> Best regards,
> Tomasz

Thanks,
Pankaj Dubey

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