From 6c723d5bd89f03fc3ef627d50f89ade054d2ee3b Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Thu, 24 Jan 2008 10:21:57 +0800 Subject: PCI: PCIE 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. Signed-off-by: Shaohua Li Signed-off-by: Greg Kroah-Hartman --- drivers/pci/probe.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'drivers/pci/probe.c') diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 4262dfec5676..9b4673df27e7 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -9,6 +9,7 @@ #include #include #include +#include #include "pci.h" #define CARDBUS_LATENCY_TIMER 176 /* secondary latency timer */ @@ -1010,6 +1011,10 @@ int pci_scan_slot(struct pci_bus *bus, int devfn) break; } } + + if (bus->self) + pcie_aspm_init_link_state(bus->self); + return nr; } -- cgit v1.2.3