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Date: Fri, 7 Oct 2011 09:51:14 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Eric Miao <eric.y.miao@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, Jason Chagas <jason.chagas@marvell.com>,
        Haojian Zhuang <haojian.zhuang@marvell.com>
Subject: Re: [PATCH 13/26] ARM: pxa: use correct __iomem annotations
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On Fri, Oct 07, 2011 at 04:11:01PM +0800, Eric Miao wrote:
> To be honest, I'd really like to keep the *_VIRT_BASE definitions to be
> type independent.
> 
> And have the actual register definitions to be casted to void __iomem *
> when being defined, e.g.
> 
> #define APBC_REG(x)	IOMEM(APBC_VIRT_BASE + (x))
> 
> #define APBC_UART1	APBC_REG(0x000)
> 
> Arnd, do we have some standard guidelines on this for all SoCs
> to follow? As I know, it's currently still being a mess.

It makes much more sense for the base address to be correctly typed (even
though it does mean a cast in the map_desc tables).  It avoids type
problems if someone does readl(APBC_VIRT_BASE + reg) somewhere, and
also avoids type problems should someone decide to pass the base address
around.