Subject: Re: IDE + CPU Scaling problem on Via EPIA systems
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Dave Jones <davej@redhat.com>
Cc: gboyce <gboyce@badbelly.com>, linux-kernel@vger.kernel.org
In-Reply-To: <20051128063212.GA18775@redhat.com>
References: <Pine.LNX.4.64.0511272350380.17020@localhost.localdomain>
	 <20051128063212.GA18775@redhat.com>
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Date: Sun, 04 Dec 2005 16:22:03 +0000
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On Llu, 2005-11-28 at 01:32 -0500, Dave Jones wrote:
> On some variants of the VIA C3, we need to quiesce all DMA operations
> before we do a speed transition. We currently don't do that.
> I do have a patch from someone which adds support in the longhaul
> driver to wait for IDE transactions to stop, but to do it cleanly,
> we really need some callbacks into the IDE layer.

I was under the impression you could turn the IO/MEM enable on the root
bridge off momentarily to get the needed DMA pause safely ? Or does it
abort rather than retry at that point ?

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