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-rw-r--r--arch/x86/kernel/pci-dma.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 1972266e8ba5..192624820217 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -9,6 +9,8 @@
#include <asm/calgary.h>
#include <asm/amd_iommu.h>
+static int forbid_dac __read_mostly;
+
struct dma_mapping_ops *dma_ops;
EXPORT_SYMBOL(dma_ops);
@@ -291,3 +293,17 @@ void pci_iommu_shutdown(void)
}
/* Must execute after PCI subsystem */
fs_initcall(pci_iommu_init);
+
+#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