linux-kernel - use {readl|writel}_relaxed instead of readl/writel in i2c-designware-core ?

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Date:	Fri, 14 Feb 2014 15:54:38 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: use {readl|writel}_relaxed instead of readl/writel in
 i2c-designware-core ?

Hi all,

The writel/readl is too expensive especially on Cortex A9 w/ outer L2 cache. This
introduce i2c read/write error on Marvell Berlin SoCs when there are L2 cache
maintenance operations at the same time.

In our internal berlin bsp, we just replaced readl/writel with the relaxed
version. But AFAIK, the "relaxed" version doesn't exist on all architectures. How
to handle this issue? 

Any suggestions are appreciated.

Thanks in advance,
Jisheng
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