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authorAndi Kleen <ak@suse.de>2007-06-20 12:23:32 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-06-20 14:27:25 -0700
commit388c19e176436707eb30a81c7e4129e08769f92b (patch)
tree168017ad573b12c35a39f52f3513c779de3fb8c8 /arch/i386/kernel
parent0b622330213ce0f0ee23199e433ed73284209b46 (diff)
downloadlinux-stericsson-388c19e176436707eb30a81c7e4129e08769f92b.tar.gz
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 <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/i386/kernel')
-rw-r--r--arch/i386/kernel/pci-dma.c27
1 files changed, 27 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 @@
#include <linux/string.h>
#include <linux/pci.h>
#include <linux/module.h>
+#include <linux/pci.h>
#include <asm/io.h>
struct dma_coherent_mem {
@@ -148,3 +149,29 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
return mem->virt_base + (pos << PAGE_SHIFT);
}
EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
+
+#ifdef CONFIG_PCI
+/* Many VIA bridges seem to corrupt data for DAC. Disable it here */
+
+int forbid_dac;
+EXPORT_SYMBOL(forbid_dac);
+
+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);
+
+static int check_iommu(char *s)
+{
+ if (!strcmp(s, "usedac")) {
+ forbid_dac = -1;
+ return 1;
+ }
+ return 0;
+}
+__setup("iommu=", check_iommu);
+#endif