The patch titled
pci-quirks: unhide 'Overflow' device on i828{6,7}5P/PE chipsets
has been added to the -mm tree. Its filename is
pci-quirks-unhide-overflow-device-on-i828675p-pe-chipsets.patch
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------------------------------------------------------
Subject: pci-quirks: unhide 'Overflow' device on i828{6,7}5P/PE chipsets
From: Michal Miroslaw <mirq-linux@xxxxxxxxxxxx>
As I found out from EDAC driver sources for i82875P some BIOSes for
i82875P/PE hide 'overflow' device 6. The same thing happens for
i82865P/PE chipsets.
After testing this patch for couple of days on my laptop (i82856P) it
looks like something is resetting device 0 (MCH) config register 0xF4 to
zero and effectively disabling the device again. The delay looks random
to me. I can easily update the register using 'hexedit
/sys/bus/pci/devices/0000\:00\:00.0/config' and see correct values in
lspci output afterwards.
Signed-off-by: Michal Miroslaw <mirq-linux@xxxxxxxxxxxx>
Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Cc: Doug Thompson <norsk5@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/pci/quirks.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff -puN drivers/pci/quirks.c~pci-quirks-unhide-overflow-device-on-i828675p-pe-chipsets drivers/pci/quirks.c
--- a/drivers/pci/quirks.c~pci-quirks-unhide-overflow-device-on-i828675p-pe-chipsets
+++ a/drivers/pci/quirks.c
@@ -2149,6 +2149,27 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AT
#endif /* CONFIG_PCI_MSI */
+/* 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_memory_controller_dev6(struct pci_dev *dev)
+{
+ u8 reg;
+
+ if (pci_read_config_byte(dev, 0xF4, ®) == 0 && !(reg & 0x02)) {
+ dev_info(&dev->dev, "Enabling MCH Memory Controller 'Overflow' Device");
+ 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_memory_controller_dev6);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82875_HB,
+ quirk_unhide_mch_memory_controller_dev6);
+
static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
struct pci_fixup *end)
{
_
Patches currently in -mm which might be from mirq-linux@xxxxxxxxxxxx are
pci-quirks-unhide-overflow-device-on-i828675p-pe-chipsets.patch
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