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Subject: Re: RFC on writel and writel_relaxed
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Will Deacon <will.deacon@arm.com>, Sinan Kaya <okaya@codeaurora.org>
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On Tue, 2018-03-27 at 15:36 +0100, Will Deacon wrote:
> > Can we say the same thing for iowrite32() and iowrite32be(). I also see wmb()
> > in front of these.
> 
> I don't think so. My reading of memory-barriers.txt says that writeX might
> expand to outX, and outX is not ordered with respect to other types of
> memory.

Ugh ?

My understanding of HW at least is the exact opposite. outX is *more*
ordered if anything, than any other accessors. IO space is completely
synchronous, non posted and ordered afaik.

Cheers,
Ben.