[PATCH V3 42/63] ST SPEAr: replace readl, writel with __raw_readl, __raw_writel in uncompress.h

stanley.miao stanley.miao at windriver.com
Fri Jan 7 04:38:11 EST 2011

Russell King - ARM Linux wrote:
> 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.
Hi, Russell, Thanks for your patient explanation.

With this in mind, I think readl_relaxed() should be better here.


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