On Thursday, September 30, 2010 09:38:28 am Matthew Garrett wrote:
> AMD's reference BIOS code had a bug that could result in the firmware
> failing to reenable the iommu on resume. It transpires that this causes
> certain less than desirable behaviour when it comes to PCI accesses, to
> whit them ending up somewhere near Bristol when the more desirable outcome
> was Edinburgh. Sadness ensues, perhaps along with filesystem corruption.
> Let's make sure that it gets turned back on.
>
> Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
> ---
> drivers/pci/quirks.c | 33 +++++++++++++++++++++++++++++++++
> 1 files changed, 33 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 89ed181..dcf9832 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -2695,6 +2695,39 @@ DECLARE_PCI_FIXUP_RESUME_EARLY(PCI_VENDOR_ID_RICOH, PCI_DEVICE_ID_RICOH_R5C832,
> #endif /*CONFIG_MMC_RICOH_MMC*/
>
>
> +#ifdef CONFIG_AMD_IOMMU
> +
> +/* Some AMD BIOSes fail to reenable the iommu on resume */
> +
> +static void amd_iommu_reenable(struct pci_dev *dev)
> +{
> + u32 ioc_feature_control;
> + struct pci_dev *iommu;
> +
> + iommu = pci_get_device(PCI_VENDOR_ID_ATI, 0x5a23, NULL);
> +
> + if (!iommu)
> + return;
> +
> + /* Select Northbridge indirect register 0x75 and enable writing */
> + pci_write_config_dword(dev, 0x60, 0x75 | (1 << 7));
> + pci_read_config_dword(dev, 0x64, &ioc_feature_control);
> +
> + /* Enable the iommu if it's vanished */
> + if (!(ioc_feature_control & 0x1))
> + pci_write_config_dword(dev, 0x64, ioc_feature_control | 1);
This sounds important and tricky enough that it'd be nice to have a
note in dmesg about what we're doing.
> + /* Disable writing again */
> + pci_write_config_dword(dev, 0x60, 0x75);
> +
> + pci_dev_put(iommu);
> +}
> +
> +DECLARE_PCI_FIXUP_RESUME_EARLY(PCI_VENDOR_ID_ATI, 0x5a10, amd_iommu_reenable);
> +DECLARE_PCI_FIXUP_RESUME_EARLY(PCI_VENDOR_ID_ATI, 0x5a12, amd_iommu_reenable);
> +DECLARE_PCI_FIXUP_RESUME_EARLY(PCI_VENDOR_ID_ATI, 0x5a13, amd_iommu_reenable);
> +#endif
> +
> static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
> struct pci_fixup *end)
> {
>
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