linux-kernel - Re: [PATCH v2 05/18] reset: Add reset_controller_of

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Date:	Tue, 10 Mar 2015 16:30:40 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Andreas Färber <afaerber@...e.de>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Rob Herring <robh+dt@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Jonathan Corbet <corbet@....net>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linus Walleij <linus.walleij@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Joe Perches <joe@...ches.com>, Antti Palosaari <crope@....fi>,
	Tejun Heo <tj@...nel.org>, Will Deacon <will.deacon@....com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Kees Cook <keescook@...omium.org>,
	Michal Marek <mmarek@...e.cz>,
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	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
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	Linux-Arch <linux-arch@...r.kernel.org>,
	"linux-api@...r.kernel.org" <linux-api@...r.kernel.org>
Subject: Re: [PATCH v2 05/18] reset: Add reset_controller_of_init() function

On Tue, Mar 10, 2015 at 3:19 PM, Arnd Bergmann <arnd@...db.de> wrote:
> On Tuesday 10 March 2015 16:28:44 Maxime Coquelin wrote:
>> 2015-03-10 16:00 GMT+01:00 Arnd Bergmann <arnd@...db.de>:
>> > On Friday 20 February 2015 19:01:04 Maxime Coquelin wrote:
>> >> Some platforms need to initialize the reset controller before the timers.
>> >>
>> >> This patch introduces a reset_controller_of_init() function that can be
>> >> called before the timers intialization.
>> >>
>> >> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@...il.com>
>> >>
>> >
>> > Not sure about this. It seems like the cleanest approach if we get
>> > a lot of these, but then again it is probably very rare, and I'd
>> > like to avoid adding such infrastructure if it's just for one
>> > SoC. Could we add a hack in the machine initialization instead?
>>
>> Sun6i also need to initialize the reset controller early. Today, they
>> hack the machine initialization.
>> With two SoCs having the same need, what should we do?
>
> Good question, I'd like to hear some other opinions on this first.

2 is still far from the common case.

>> > I think ideally this would be done in the boot loader before we
>> > even start Linux, but I don't know if that's possible for you.
>>
>> From what I understand, the only constraint is to perform it after the
>> clock is enabled.
>> So this should be possible to do it in the bootloader, but it means
>> also adding timers clocks ungating in the bootloader.
>
> Ungating the timer clock input seems like a reasonable thing to
> do for the bootloader, I think a lot of platforms rely on this
> elsewhere (but enough of them don't, which is why we have the
> early clk init).

+1

If the bootloader is u-boot, then you need a timer anyway.

Rob
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