[PATCH 2.6.29-rc7 2/2] x86: disallow DAC for MCP51 PCI bridge

[Tejun Heo <tj@kernel.org>]

MCP51 corrupts DAC transfers.  Disallow it.  Reported by pgnet on
bnc#463829.

  https://bugzilla.novell.com/show_bug.cgi?id=463829

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: pgnet <pgnet.trash@gmail.com>
---
 arch/x86/kernel/pci-dma.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index b254285..7b61798 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -296,4 +296,18 @@ static __devinit void via_no_dac(struct pci_dev *dev)
 	}
 }
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac);
+
+/*
+ * MCP51 PCI bridge corrupts data for DAC.  Disable it.  Reported in
+ * bnc#463829.
+ */
+static __devinit void mcp51_no_dac(struct pci_dev *dev)
+{
+	if (forbid_dac == 0) {
+		printk(KERN_INFO
+		       "PCI: MCP51 PCI bridge detected. Disabling DAC.\n");
+		forbid_dac = 1;
+	}
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NVIDIA, 0x026f, mcp51_no_dac);
 #endif