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From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Joerg Roedel <joerg.roedel@amd.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	stable@kernel.org
Subject: Re: [PATCH 2/3] x86/amd-iommu: Work around S3 BIOS bug
Date: Thu, 30 Sep 2010 21:21:04 +0100	[thread overview]
Message-ID: <20100930202104.GA20495@srcf.ucam.org> (raw)
In-Reply-To: <1285253089-4570-3-git-send-email-joerg.roedel@amd.com>

On Thu, Sep 23, 2010 at 04:44:48PM +0200, Joerg Roedel wrote:
> +static void iommu_apply_quirks(struct amd_iommu *iommu)
> +{
> +	if (is_rd890_iommu(iommu->dev)) {
> +		pci_write_config_dword(iommu->dev, 0xf0, iommu->cache_cfg[0]);
> +		pci_write_config_dword(iommu->dev, 0xf4, iommu->cache_cfg[1]);
> +		pci_write_config_dword(iommu->dev, 0xf8, iommu->cache_cfg[2]);
> +		pci_write_config_dword(iommu->dev, 0xfc, iommu->cache_cfg[3]);
> +	}
> +}
> +

This doesn't look right. 0xf0-0xff are for indexed register access, so 
what you're doing here is just restoring the last of each of those 
registers that the BIOS programmed - and if the BIOS cleared the 
writable flag afterwards, you're not even doing that.

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

  reply	other threads:[~2010-09-30 20:21 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-23 14:44 [git pull] AMD IOMMU fixes for 2.6.36 Joerg Roedel
2010-09-23 14:44 ` [PATCH 1/3] x86/amd-iommu: Set iommu configuration flags in enable-loop Joerg Roedel
2010-09-23 14:44 ` [PATCH 2/3] x86/amd-iommu: Work around S3 BIOS bug Joerg Roedel
2010-09-30 20:21   ` Matthew Garrett [this message]
2010-10-01  9:07     ` Roedel, Joerg
2010-09-23 14:44 ` [PATCH 3/3] x86/amd-iommu: Fix rounding-bug in __unmap_single Joerg Roedel
2010-09-24  9:21 ` [git pull] AMD IOMMU fixes for 2.6.36 Ingo Molnar

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