From 5f39e6705faade2e89d119958a8c51b9b6e2c53c Mon Sep 17 00:00:00 2001 From: Jon Mason Date: Mon, 3 Oct 2011 09:50:20 -0500 Subject: 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 Acked-by: Benjamin Herrenschmidt Signed-off-by: Linus Torvalds --- drivers/pci/probe.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'drivers/pci/probe.c') diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index f3f94a5c068f..6ab6bd3df4b2 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1458,12 +1458,24 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data) */ void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss) { - u8 smpss = mpss; + u8 smpss; if (!pci_is_pcie(bus->self)) return; + if (pcie_bus_config == PCIE_BUS_TUNE_OFF) + return; + + /* FIXME - Peer to peer DMA is possible, though the endpoint would need + * to be aware to the MPS of the destination. To work around this, + * simply force the MPS of the entire system to the smallest possible. + */ + if (pcie_bus_config == PCIE_BUS_PEER2PEER) + smpss = 0; + if (pcie_bus_config == PCIE_BUS_SAFE) { + smpss = mpss; + pcie_find_smpss(bus->self, &smpss); pci_walk_bus(bus, pcie_find_smpss, &smpss); } -- cgit v1.2.1