Re: [PATCH] document mmiowb and readX_relaxed a bit more indeviceiobook.tmpl

[Benjamin Herrenschmidt]

On Fri, 2004-10-29 at 17:47 -0700, Jesse Barnes wrote:
> This is a small patch to deviceiobook.tmpl to describe the new mmiowb routine 
> a bit more completely.  I've also updated it to provide pointers to drivers 
> that do write flushing, use mmiowb, and use the readX_relaxed routines.

It's all good, but your semantics and description are very tailored to
your specific arch problem vs. unlock.

What about my suggestion of defining a broader semantic of mmiowb() as
beeing a barrier ordering MMIOs vs. the rest of the world ? The later
includes stores to memory _and_ spinlock/unlock.

I still intend to eventually make good use of that on ppc64 to get rid
of the expensive barriers we had to put in our writeX() implementations,
though I didn't have time to work on that yet.

Ben.


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