1 files changed, 18 insertions, 0 deletions

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 91443361cb67..48cccbe51aa5 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -1,12 +1,16 @@
 #include <linux/dma-mapping.h>
 #include <linux/dmar.h>
 #include <linux/bootmem.h>
+#include <linux/pci.h>
 
 #include <asm/proto.h>
 #include <asm/dma.h>
 #include <asm/gart.h>
 #include <asm/calgary.h>
 
+int forbid_dac __read_mostly;
+EXPORT_SYMBOL(forbid_dac);
+
 const struct dma_mapping_ops *dma_ops;
 EXPORT_SYMBOL(dma_ops);
 
@@ -121,3 +125,17 @@ 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