From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
Date: Fri, 7 Jan 2011 09:17:20 +0000
Subject: [PATCH V3 42/63] ST SPEAr: replace readl, writel with
	__raw_readl, __raw_writel in uncompress.h
In-Reply-To: <4D2679D1.3080005@windriver.com>
References: <cover.1292833228.git.viresh.kumar@st.com>
	<73a77c388f8d151ce5bc70000832fbb518babe3b.1292833229.git.viresh.kumar@st.com>
	<4D2679D1.3080005@windriver.com>
Message-ID: <20110107091720.GM31708@n2100.arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Fri, Jan 07, 2011 at 10:26:25AM +0800, stanley.miao wrote:
> Viresh Kumar wrote:
>> readl also calls outer cache maintainance operations 
>
> I use readl here on spear13xx. It works fine.
> This is the definition of readl, could you tell me which code calls  
> outer cache maintainance ?
>
> #define readl(c) ({ __u32 __v = le32_to_cpu((__force __le32) \
>                                        __raw_readl(__mem_pci(c))); __v; })

#define readl(c)                ({ u32 __v = readl_relaxed(c); __iormb(); __v; })

is how it's now defined, and __iormb() is defined to be rmb() on ARMv7+,
which translates to a dmb.

writel() on the other hand is less straight forward.  It uses __iowmb()
which translates to a wmb() on ARMv7+, which is a dsb and an outer cache
sync operation.  This will fail in the decompressor code as there's no
outer cache support there.