From 27d868b5e6cfaee4fec66b388e4085ff94050fa7 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Mon, 24 Aug 2015 08:48:16 -0500 Subject: PCI: Set MPS to match upstream bridge Firmware typically configures the PCIe fabric with a consistent Max Payload Size setting based on the devices present at boot. A hot-added device typically has the power-on default MPS setting (128 bytes), which may not match the fabric. The previous Linux default, in the absence of any "pci=pcie_bus_*" options, was PCIE_BUS_TUNE_OFF, in which we never touch MPS, even for hot-added devices. Add a new default setting, PCIE_BUS_DEFAULT, in which we make sure every device's MPS setting matches the upstream bridge. This makes it more likely that a hot-added device will work in a system with optimized MPS configuration. Note that if we hot-add a device that only supports 128-byte MPS, it still likely won't work because we don't reconfigure the rest of the fabric. Booting with "pci=pcie_bus_peer2peer" is a workaround for this because it sets MPS to 128 for everything. [bhelgaas: changelog, new default, rework for pci_configure_device() path] Tested-by: Keith Busch Tested-by: Jordan Hargrave Signed-off-by: Keith Busch Signed-off-by: Bjorn Helgaas Acked-by: Yinghai Lu --- drivers/pci/quirks.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/pci/quirks.c') diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index e9fd0e90fa3b..55f2c208bd0e 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -2862,7 +2862,8 @@ static void quirk_intel_mc_errata(struct pci_dev *dev) int err; u16 rcc; - if (pcie_bus_config == PCIE_BUS_TUNE_OFF) + if (pcie_bus_config == PCIE_BUS_TUNE_OFF || + pcie_bus_config == PCIE_BUS_DEFAULT) return; /* Intel errata specifies bits to change but does not say what they are. -- cgit v1.2.3