linux-kernel - Re: [PATCH 1/3] ARM: uniphier: add outer cache support

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Date:	Wed, 26 Aug 2015 10:38:59 +0900
From:	Masahiro Yamada <yamada.masahiro@...ionext.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	arm@...nel.org, Jiri Slaby <jslaby@...e.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Kumar Gala <galak@...eaurora.org>,
	Jungseung Lee <js07.lee@...il.com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Herring <robh+dt@...nel.org>, Tejun Heo <tj@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Florian Fainelli <f.fainelli@...il.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	devicetree@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	Nathan Lynch <nathan_lynch@...tor.com>,
	Kees Cook <keescook@...omium.org>,
	Paul Bolle <pebolle@...cali.nl>,
	Greg KH <gregkh@...uxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Joe Perches <joe@...ches.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH 1/3] ARM: uniphier: add outer cache support

Hi Arnd,


2015-08-25 4:59 GMT+09:00 Arnd Bergmann <arnd@...db.de>:
> On Monday 24 August 2015 11:18:10 Masahiro Yamada wrote:
>> diff --git a/Documentation/devicetree/bindings/arm/uniphier/cache-uniphier.txt b/Documentation/devicetree/bindings/arm/uniphier/cache-uniphier.txt
>> new file mode 100644
>> index 0000000..6428289
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/uniphier/cache-uniphier.txt
>> @@ -0,0 +1,30 @@
>> +UniPhier outer cache controller
>> +
>> +UniPhier SoCs are integrated with a level 2 cache controller that resides
>> +outside of the ARM cores, some of them also have a level 3 cache controller.
>> +
>> +Required properties:
>> +- compatible: should be one of the followings:
>> +       "socionext,uniphier-l2-cache"   (L2 cache)
>> +       "socionext,uniphier-l3-cache"   (L3 cache)
>> +- reg: offsets and lengths of the register sets for the device.  It should
>> +  contain 3 regions: control registers, revision registers, operation
>> +  registers, in this order.
>> +
>> +The L2 cache must exist to use the L3 cache; adding only an L3 cache device
>> +node to the device tree causes the initialization failure of the whole outer
>> +cache system.
>>
>
> How much does this outer cache have in common with the l2x0/pl310 cache
> controller model?

Nothing.

This outer cache is not a variant of l2x0/pl310.
It was designed only for our SoCs from scratch.


> Would it make sense to at least share the
> common entry point at l2x0_of_init() so you don't need to call it from
> the platform file?

I do not think so.


l2x0_of_init() checks L2X0_AUX_CTRL register,
but the cache-uniphier does not have such register,
so the boot code crashes.



BTW, what makes l2x0_of_init() so special?

Only L2x0/L310 and variants can be initialized
directly from init_IRQ().

Moreover, outer-cache init seems to be unrelated to
IRQ init.


-- 
Best Regards
Masahiro Yamada
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