linux-kernel - Re: [PATCH] pci: Reenable the AMD IOMMU if it's mysteriously vanished over suspend

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Date:	Thu, 30 Sep 2010 20:05:36 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Joerg Roedel <joro@...tes.org>
Cc:	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	joerg.roedel@....com, jbarnes@...tuousgeek.org
Subject: Re: [PATCH] pci: Reenable the AMD IOMMU if it's mysteriously
	vanished over suspend

On Thu, Sep 30, 2010 at 08:43:01PM +0200, Joerg Roedel wrote:

> Enabling the IOMMU device is only part of what the BIOS is supposed to
> do to get the IOMMU ready for the OS. A handful of registers in the
> config space of the device and the IOMMU MMIO region must also be
> restored. Thats the simple part. The IOMMU device also spans two
> indirect register spaces to configure the IOMMU caches. I have no idea
> yet how this need to be configured. The plan is definitly to
> work-around a missing IOMMU device in the IOMMU driver. But I am still
> talking to some people to find out what exactly must be done, especially
> with the indirect register spaces.

Chapter 8 of the register setup guide seems to have something on this - 
I'll try saving and restoring all of the setup it performs to see if it 
improves things.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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