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Date: Fri, 21 Mar 2008 14:54:18 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Andi Kleen <andi@firstfloor.org>, Ingo Molnar <mingo@elte.hu>,
       kernel list <linux-kernel@vger.kernel.org>, Greg KH <greg@kroah.com>
Subject: Re: iommu breaks usb after resume
Message-ID: <20080321135418.GB2346@one.firstfloor.org>
References: <20080320111429.GA14764@elf.ucw.cz>
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On Thu, Mar 20, 2008 at 12:14:29PM +0100, Pavel Machek wrote:
> Hi!
> 
> On 64-bit machine with 4GB ram (8core from amd), iommu breaks USB
> after swsusp. iommu=soft fixes that issue.
> 
> I guess iommu handling in arch/x86/kernel/ should have some
> suspend/resume support, as it manipulates hardware registers...?

AGP suspend/resume should already handle restoring of the aperture
and the IOMMU code uses the same.  It has not other state. It might not work 
when the AGP driver is not compiled in/loaded though (I suspect
that is what happened to you) One simple fix would be to just enforce
that in Kconfig when suspend/resume is enabled.

-Andi