From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
Subject: Re: [PATCH v4 1/8] ARM: mediatek: Add basic support for mt8127
Date: Tue, 04 Nov 2014 08:39:55 +0100
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References: <1413973797-17619-1-git-send-email-yingjoe.chen@mediatek.com> <CABuKBeLYMbD-dV_25FJd_NE1RgfVkgF+SoCiAx9O9jKUUAcexA@mail.gmail.com> <1415083006.10186.85.camel@mtksdaap41>
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To: HC Yen <hc.yen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
Cc: Matthias Brugger <matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, "Joe. C" <yingjoe.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>, Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, arm-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, Ian Campbell <ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>, Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>, Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>, Olof Johansson <olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org>, "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" <linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>, srv_heupstream <srv_heupstream-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>, Yingjoe Chen <yingjoe.chen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, huang eddie <eddie.huang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>, Nathan Chung <nathan.chung-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>, Yuhau Chen <yh.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>, Sascha Hauer <kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
List-Id: devicetree@vger.kernel.org

On Tuesday 04 November 2014 14:36:45 HC Yen wrote:
> > > +
> > > +#include <dt-bindings/interrupt-controller/irq.h>
> > > +#include <dt-bindings/interrupt-controller/arm-gic.h>
> > > +#include "skeleton64.dtsi"
> > 
> > Cortex a7 is 32 bits, right? So why do you use skeleton64.dtsi?
> 
> Cortex-A7 is 32-bit, but that doesn't mean it can only have 32-bit
> physical address.  With LPAE enabled, we can have physical address more
> than 32 bits.
> 
> The main difference between "skeleton64.dtsi" and "skeleton.dtsi" is
> "#address-cells" property set to 2.  Although there are few sources
> using "skeleton64.dtsi", some of them write "#address-cells = <2>"
> directly in order to have 64-bit address space.  ARM's TC2 reference
> platform (vexpress-v2p-ca15_a7.dts) is an example.
> 
> Some of MediaTek ARMv7 SoCs support address space larger than 4GB. It
> will be convenient to share the sources if we all use 64-bit device
> tree.

Right, in general, I'd use #address-cells=<2> for Cortex-A7/A15/A17.

	Arnd
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