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-rw-r--r--arch/i386/kernel/pci-dma.c27
-rw-r--r--arch/x86_64/kernel/pci-dma.c12
-rw-r--r--include/asm-i386/dma-mapping.h6
3 files changed, 45 insertions, 0 deletions
diff --git a/arch/i386/kernel/pci-dma.c b/arch/i386/kernel/pci-dma.c
index 30b754f7cbec..048f09b62553 100644
--- a/arch/i386/kernel/pci-dma.c
+++ b/arch/i386/kernel/pci-dma.c
@@ -12,6 +12,7 @@
12#include <linux/string.h> 12#include <linux/string.h>
13#include <linux/pci.h> 13#include <linux/pci.h>
14#include <linux/module.h> 14#include <linux/module.h>
15#include <linux/pci.h>
15#include <asm/io.h> 16#include <asm/io.h>
16 17
17struct dma_coherent_mem { 18struct dma_coherent_mem {
@@ -148,3 +149,29 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
148 return mem->virt_base + (pos << PAGE_SHIFT); 149 return mem->virt_base + (pos << PAGE_SHIFT);
149} 150}
150EXPORT_SYMBOL(dma_mark_declared_memory_occupied); 151EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
152
153#ifdef CONFIG_PCI
154/* Many VIA bridges seem to corrupt data for DAC. Disable it here */
155
156int forbid_dac;
157EXPORT_SYMBOL(forbid_dac);
158
159static __devinit void via_no_dac(struct pci_dev *dev)
160{
161 if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI && forbid_dac == 0) {
162 printk(KERN_INFO "PCI: VIA PCI bridge detected. Disabling DAC.\n");
163 forbid_dac = 1;
164 }
165}
166DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac);
167
168static int check_iommu(char *s)
169{
170 if (!strcmp(s, "usedac")) {
171 forbid_dac = -1;
172 return 1;
173 }
174 return 0;
175}
176__setup("iommu=", check_iommu);
177#endif
diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c
index 651ccfb06697..9f80aad3fe2d 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)
322 return 0; 322 return 0;
323} 323}
324 324
325#ifdef CONFIG_PCI
326/* Many VIA bridges seem to corrupt data for DAC. Disable it here */
327
328static __devinit void via_no_dac(struct pci_dev *dev)
329{
330 if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI && forbid_dac == 0) {
331 printk(KERN_INFO "PCI: VIA PCI bridge detected. Disabling DAC.\n");
332 forbid_dac = 1;
333 }
334}
335DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac);
336#endif
325/* Must execute after PCI subsystem */ 337/* Must execute after PCI subsystem */
326fs_initcall(pci_iommu_init); 338fs_initcall(pci_iommu_init);
diff --git a/include/asm-i386/dma-mapping.h b/include/asm-i386/dma-mapping.h
index 183eebeebbdc..f1d72d177f68 100644
--- a/include/asm-i386/dma-mapping.h
+++ b/include/asm-i386/dma-mapping.h
@@ -123,6 +123,8 @@ dma_mapping_error(dma_addr_t dma_addr)
123 return 0; 123 return 0;
124} 124}
125 125
126extern int forbid_dac;
127
126static inline int 128static inline int
127dma_supported(struct device *dev, u64 mask) 129dma_supported(struct device *dev, u64 mask)
128{ 130{
@@ -134,6 +136,10 @@ dma_supported(struct device *dev, u64 mask)
134 if(mask < 0x00ffffff) 136 if(mask < 0x00ffffff)
135 return 0; 137 return 0;
136 138
139 /* Work around chipset bugs */
140 if (forbid_dac > 0 && mask > 0xffffffffULL)
141 return 0;
142
137 return 1; 143 return 1;
138} 144}
139 145