PCI: Disable MPS configuration by default

Add the ability to disable PCI-E MPS turning and using the BIOS
configured MPS defaults.  Due to the number of issues recently
discovered on some x86 chipsets, make this the default behavior.

Also, add the option for peer to peer DMA MPS configuration.  Peer to
peer DMA is outside the scope of this patch, but MPS configuration could
prevent it from working by having the MPS on one root port different
than the MPS on another.  To work around this, simply make the system
wide MPS the smallest possible value (128B).

Signed-off-by: Jon Mason <mason@myri.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 8c230cbcbb4..9fc01226055 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -621,8 +621,9 @@ struct pci_driver {
 extern void pcie_bus_configure_settings(struct pci_bus *bus, u8 smpss);
 
 enum pcie_bus_config_types {
-        PCIE_BUS_PERFORMANCE,
+        PCIE_BUS_TUNE_OFF,
         PCIE_BUS_SAFE,
+        PCIE_BUS_PERFORMANCE,
         PCIE_BUS_PEER2PEER,
 };