From 388c19e176436707eb30a81c7e4129e08769f92b Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 20 Jun 2007 12:23:32 +0200 Subject: x86: Disable DAC on VIA bridges Several reports that VIA bridges don't support DAC and corrupt data. I don't know if it's fixed, but let's just blacklist them all for now. It can be overwritten with iommu=usedac Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/pci-dma.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'arch/x86_64/kernel') diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c index 651ccfb0669..9f80aad3fe2 100644 --- a/arch/x86_64/kernel/pci-dma.c +++ b/arch/x86_64/kernel/pci-dma.c @@ -322,5 +322,17 @@ static int __init pci_iommu_init(void) return 0; } +#ifdef CONFIG_PCI +/* Many VIA bridges seem to corrupt data for DAC. Disable it here */ + +static __devinit void via_no_dac(struct pci_dev *dev) +{ + if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI && forbid_dac == 0) { + printk(KERN_INFO "PCI: VIA PCI bridge detected. Disabling DAC.\n"); + forbid_dac = 1; + } +} +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac); +#endif /* Must execute after PCI subsystem */ fs_initcall(pci_iommu_init); -- cgit v1.2.3