Commit b0e85c3c authored by Jim Quinlan's avatar Jim Quinlan Committed by Bjorn Helgaas

PCI: Add Kconfig options for MPS/MRRS strategy

Add Kconfig options for changing the default pcie_bus_config, i.e., the
strategy for configuration MPS and MRRS, in the same manner as the
CONFIG_PCIEASPM_XXXX choice.  The pci_bus_config setting may still be
overridden by kernel command-line parameters, e.g.,
"pci=pcie_bus_tune_off".

[bhelgaas: depend on EXPERT, tweak help texts]
Link: https://lore.kernel.org/r/20200928194651.5393-2-james.quinlan@broadcom.comSigned-off-by: default avatarJim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 877c1a5f
...@@ -187,6 +187,68 @@ config PCI_HYPERV ...@@ -187,6 +187,68 @@ config PCI_HYPERV
The PCI device frontend driver allows the kernel to import arbitrary The PCI device frontend driver allows the kernel to import arbitrary
PCI devices from a PCI backend to support PCI driver domains. PCI devices from a PCI backend to support PCI driver domains.
choice
prompt "PCI Express hierarchy optimization setting"
default PCIE_BUS_DEFAULT
depends on PCI && EXPERT
help
MPS (Max Payload Size) and MRRS (Max Read Request Size) are PCIe
device parameters that affect performance and the ability to
support hotplug and peer-to-peer DMA.
The following choices set the MPS and MRRS optimization strategy
at compile-time. The choices are the same as those offered for
the kernel command-line parameter 'pci', i.e.,
'pci=pcie_bus_tune_off', 'pci=pcie_bus_safe',
'pci=pcie_bus_perf', and 'pci=pcie_bus_peer2peer'.
This is a compile-time setting and can be overridden by the above
command-line parameters. If unsure, choose PCIE_BUS_DEFAULT.
config PCIE_BUS_TUNE_OFF
bool "Tune Off"
depends on PCI
help
Use the BIOS defaults; don't touch MPS at all. This is the same
as booting with 'pci=pcie_bus_tune_off'.
config PCIE_BUS_DEFAULT
bool "Default"
depends on PCI
help
Default choice; ensure that the MPS matches upstream bridge.
config PCIE_BUS_SAFE
bool "Safe"
depends on PCI
help
Use largest MPS that boot-time devices support. If you have a
closed system with no possibility of adding new devices, this
will use the largest MPS that's supported by all devices. This
is the same as booting with 'pci=pcie_bus_safe'.
config PCIE_BUS_PERFORMANCE
bool "Performance"
depends on PCI
help
Use MPS and MRRS for best performance. Ensure that a given
device's MPS is no larger than its parent MPS, which allows us to
keep all switches/bridges to the max MPS supported by their
parent. This is the same as booting with 'pci=pcie_bus_perf'.
config PCIE_BUS_PEER2PEER
bool "Peer2peer"
depends on PCI
help
Set MPS = 128 for all devices. MPS configuration effected by the
other options could cause the MPS on one root port to be
different than that of the MPS on another, which may cause
hot-added devices or peer-to-peer DMA to fail. Set MPS to the
smallest possible value (128B) system-wide to avoid these issues.
This is the same as booting with 'pci=pcie_bus_peer2peer'.
endchoice
source "drivers/pci/hotplug/Kconfig" source "drivers/pci/hotplug/Kconfig"
source "drivers/pci/controller/Kconfig" source "drivers/pci/controller/Kconfig"
source "drivers/pci/endpoint/Kconfig" source "drivers/pci/endpoint/Kconfig"
......
...@@ -101,7 +101,19 @@ unsigned long pci_hotplug_mmio_pref_size = DEFAULT_HOTPLUG_MMIO_PREF_SIZE; ...@@ -101,7 +101,19 @@ unsigned long pci_hotplug_mmio_pref_size = DEFAULT_HOTPLUG_MMIO_PREF_SIZE;
#define DEFAULT_HOTPLUG_BUS_SIZE 1 #define DEFAULT_HOTPLUG_BUS_SIZE 1
unsigned long pci_hotplug_bus_size = DEFAULT_HOTPLUG_BUS_SIZE; unsigned long pci_hotplug_bus_size = DEFAULT_HOTPLUG_BUS_SIZE;
/* PCIe MPS/MRRS strategy; can be overridden by kernel command-line param */
#ifdef CONFIG_PCIE_BUS_TUNE_OFF
enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_TUNE_OFF;
#elif defined CONFIG_PCIE_BUS_SAFE
enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_SAFE;
#elif defined CONFIG_PCIE_BUS_PERFORMANCE
enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_PERFORMANCE;
#elif defined CONFIG_PCIE_BUS_PEER2PEER
enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_PEER2PEER;
#else
enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_DEFAULT; enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_DEFAULT;
#endif
/* /*
* The default CLS is used if arch didn't set CLS explicitly and not * The default CLS is used if arch didn't set CLS explicitly and not
......
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