[PATCH 6/8] Disable MSI by default on non-PCI-E chipset

[Brice Goglin <brice@myri.com>]

[PATCH 6/8] Disable MSI by default on non-PCI-E chipset

Most PCI-E chipsets support MSI while several non-PCI-E don't.
Disable MSI when the associated root chipset is not a PCI-E one
and does not have the PCI_BUS_FLAGS_MSI flag.
On PCI-E chipset, MSI are enabled unless PCI_BUS_FLAGS_NO_MSI
is not set.

Signed-off-by: Brice Goglin <brice@myri.com>
---
 drivers/pci/msi.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

Index: linux-mm/drivers/pci/msi.c
===================================================================
--- linux-mm.orig/drivers/pci/msi.c	2006-06-17 23:07:43.000000000 -0400
+++ linux-mm/drivers/pci/msi.c	2006-06-17 23:11:00.000000000 -0400
@@ -921,11 +921,17 @@
 	while (pdev->bus && pdev->bus->self)
 		pdev = pdev->bus->self;
 
-	/* check its bus flags */
-	if (pdev->subordinate->bus_flags & PCI_BUS_FLAGS_NO_MSI)
+	if (pci_find_capability(pdev, PCI_CAP_ID_EXP)) {
+		/* PCI Express bridge, enable MSI, except when blacklisted */
+		if (pdev->subordinate->bus_flags & PCI_BUS_FLAGS_NO_MSI)
+			return -1;
+		return 0;
+	} else {
+		/* non PCI Express, disable MSI, except when whitelisted */
+		if (pdev->subordinate->bus_flags & PCI_BUS_FLAGS_MSI)
+			return 0;
 		return -1;
-
-	return 0;
+	}
 }
 
 /**