Subject: Re: [PATCH] document mmiowb and readX_relaxed a bit more in
	deviceiobook.tmpl
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Jesse Barnes <jbarnes@engr.sgi.com>
Cc: Andrew Morton <akpm@osdl.org>,
       Linux Kernel list <linux-kernel@vger.kernel.org>
In-Reply-To: <200410291747.24035.jbarnes@engr.sgi.com>
References: <200410291747.24035.jbarnes@engr.sgi.com>
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Date: Sat, 30 Oct 2004 12:35:56 +1000
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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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