1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index a778c84d04a9..15a8ab7ea911 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2017,6 +2017,28 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_BROADCOM,
                         PCI_DEVICE_ID_NX2_5709S,
                         quirk_brcm_570x_limit_vpd);
 
+/* Originally in EDAC sources for i82875P:
+ * Intel tells BIOS developers to hide device 6 which
+ * configures the overflow device access containing
+ * the DRBs - this is where we expose device 6.
+ * http://www.x86-secret.com/articles/tweak/pat/patsecrets-2.htm
+ */
+static void __devinit quirk_unhide_mch_dev6(struct pci_dev *dev)
+{
+        u8 reg;
+
+        if (pci_read_config_byte(dev, 0xF4, &reg) == 0 && !(reg & 0x02)) {
+                dev_info(&dev->dev, "Enabling MCH 'Overflow' Device\n");
+                pci_write_config_byte(dev, 0xF4, reg | 0x02);
+        }
+}
+
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82865_HB,
+                        quirk_unhide_mch_dev6);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82875_HB,
+                        quirk_unhide_mch_dev6);
+
+
 #ifdef CONFIG_PCI_MSI
 /* Some chipsets do not support MSI. We cannot easily rely on setting
  * PCI_BUS_FLAGS_NO_MSI in its bus flags because there are actually