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authorKeith Busch <keith.busch@intel.com>2015-08-24 16:48:16 +0300
committerBjorn Helgaas <bhelgaas@google.com>2015-08-24 16:48:16 +0300
commit27d868b5e6cfaee4fec66b388e4085ff94050fa7 (patch)
tree9df429169a5671c49c70b0ac34c8ba95fb1e21b7 /drivers/pci/quirks.c
parent9dae3a97297f71e884ed8e7664955bcacb86f010 (diff)
downloadlinux-27d868b5e6cfaee4fec66b388e4085ff94050fa7.tar.xz
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 <keith.busch@intel.com> Tested-by: Jordan Hargrave <jharg93@gmail.com> Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Yinghai Lu <yinghai@kernel.org>
Diffstat (limited to 'drivers/pci/quirks.c')
-rw-r--r--drivers/pci/quirks.c3
1 files changed, 2 insertions, 1 deletions
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.