Re: [PATCH] ARM: Gemini: Add support for PCI BUS

[Sergei Shtylyov]

Hello.

On 29-11-2010 19:45, Arnd Bergmann wrote:

> > > The I/O ordering is probably not what you think it is.
> > > There is no ordering guarantee between __raw_writel and
> > > spin_lock/spin_unlock, so you really should be using
> > > readl/writel.

> > No he really should NOT use readl/writel. The ONLY difference
> > between readl/writel and __raw_readl/__raw_writel is endianess
> > conversion. __raw_*l is not doing it. Which to use depend only
> > on HW.

> There are many differences between readl and __raw_readl, including

> * __raw_readl does not have barriers and does not serialize with
>    spinlocks, so it breaks on out-of-order CPUs.
> * __raw_readl does not have a specific endianess, while readl is
>    fixed little-endian,

   I know I'm late but readl()/writel() are CPU-endian, not LE.

WBR, Sergei
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