diff options
| author | Keith Busch <keith.busch@intel.com> | 2015-08-24 08:48:16 -0500 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2015-08-24 08:48:16 -0500 |
| commit | 27d868b5e6cfaee4fec66b388e4085ff94050fa7 (patch) | |
| tree | 9df429169a5671c49c70b0ac34c8ba95fb1e21b7 /include/linux/pci.h | |
| parent | 9dae3a97297f71e884ed8e7664955bcacb86f010 (diff) | |
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 'include/linux/pci.h')
| -rw-r--r-- | include/linux/pci.h | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/include/linux/pci.h b/include/linux/pci.h index 4d4f9d29fcc9..0007942923a7 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -738,10 +738,11 @@ struct pci_driver { void pcie_bus_configure_settings(struct pci_bus *bus); enum pcie_bus_config_types { - PCIE_BUS_TUNE_OFF, - PCIE_BUS_SAFE, - PCIE_BUS_PERFORMANCE, - PCIE_BUS_PEER2PEER, + PCIE_BUS_TUNE_OFF, /* don't touch MPS at all */ + PCIE_BUS_DEFAULT, /* ensure MPS matches upstream bridge */ + PCIE_BUS_SAFE, /* use largest MPS boot-time devices support */ + PCIE_BUS_PERFORMANCE, /* use MPS and MRRS for best performance */ + PCIE_BUS_PEER2PEER, /* set MPS = 128 for all devices */ }; extern enum pcie_bus_config_types pcie_bus_config; |