4 files changed, 16 insertions, 9 deletions

diff --git a/arch/ia64/include/asm/iommu.h b/arch/ia64/include/asm/iommu.h
index 5fb2bb93de3b..0490794fe4aa 100644
--- a/arch/ia64/include/asm/iommu.h
+++ b/arch/ia64/include/asm/iommu.h
@@ -11,6 +11,5 @@ extern int force_iommu, no_iommu;
 extern int iommu_detected;
 extern void iommu_dma_init(void);
 extern void machvec_init(const char *name);
-extern int forbid_dac;
 
 #endif
diff --git a/arch/ia64/kernel/pci-dma.c b/arch/ia64/kernel/pci-dma.c
index 10a75b557650..031abbf9c875 100644
--- a/arch/ia64/kernel/pci-dma.c
+++ b/arch/ia64/kernel/pci-dma.c
@@ -89,13 +89,6 @@ int iommu_dma_supported(struct device *dev, u64 mask)
 {
         struct dma_mapping_ops *ops = get_dma_ops(dev);
 
-#ifdef CONFIG_PCI
-        if (mask > 0xffffffff && forbid_dac > 0) {
-                dev_info(dev, "Disallowing DAC for device\n");
-                return 0;
-        }
-#endif
-
         if (ops->dma_supported_op)
                 return ops->dma_supported_op(dev, mask);
 
diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h
index 98e28ea8cd16..e4a552d44465 100644
--- a/arch/x86/include/asm/iommu.h
+++ b/arch/x86/include/asm/iommu.h
@@ -7,7 +7,6 @@ extern struct dma_mapping_ops nommu_dma_ops;
 extern int force_iommu, no_iommu;
 extern int iommu_detected;
 extern int dmar_disabled;
-extern int forbid_dac;
 
 extern unsigned long iommu_nr_pages(unsigned long addr, unsigned long len);
 
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