From 7d715a6c1ae5785d00fb9a876b5abdfc43abc44b Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Mon, 25 Feb 2008 09:46:41 +0800 Subject: PCI: add PCI Express ASPM support PCI Express ASPM defines a protocol for PCI Express components in the D0 state to reduce Link power by placing their Links into a low power state and instructing the other end of the Link to do likewise. This capability allows hardware-autonomous, dynamic Link power reduction beyond what is achievable by software-only controlled power management. However, The device should be configured by software appropriately. Enabling ASPM will save power, but will introduce device latency. This patch adds ASPM support in Linux. It introduces a global policy for ASPM, a sysfs file /sys/module/pcie_aspm/parameters/policy can control it. The interface can be used as a boot option too. Currently we have below setting: -default, BIOS default setting -powersave, highest power saving mode, enable all available ASPM state and clock power management -performance, highest performance, disable ASPM and clock power management By default, the 'default' policy is used currently. In my test, power difference between powersave mode and performance mode is about 1.3w in a system with 3 PCIE links. Note: some devices might not work well with aspm, either because chipset issue or device issue. The patch provide API (pci_disable_link_state), driver can disable ASPM for specific device. Signed-off-by: Shaohua Li Signed-off-by: Greg Kroah-Hartman --- drivers/pci/pcie/Kconfig | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'drivers/pci/pcie/Kconfig') diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig index 287a9311716..25b04fb2517 100644 --- a/drivers/pci/pcie/Kconfig +++ b/drivers/pci/pcie/Kconfig @@ -26,3 +26,23 @@ config HOTPLUG_PCI_PCIE When in doubt, say N. source "drivers/pci/pcie/aer/Kconfig" + +# +# PCI Express ASPM +# +config PCIEASPM + bool "PCI Express ASPM support(Experimental)" + depends on PCI && EXPERIMENTAL && PCIEPORTBUS + default y + help + This enables PCI Express ASPM (Active State Power Management) and + Clock Power Management. ASPM supports state L0/L0s/L1. + + When in doubt, say N. +config PCIEASPM_DEBUG + bool "Debug PCI Express ASPM" + depends on PCIEASPM + default n + help + This enables PCI Express ASPM debug support. It will add per-device + interface to control ASPM. -- cgit v1.2.3-70-g09d2