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authorShaohua Li <shaohua.li@intel.com>2008-02-25 09:46:41 +0800
committerGreg Kroah-Hartman <gregkh@suse.de>2008-04-20 21:47:03 -0700
commit7d715a6c1ae5785d00fb9a876b5abdfc43abc44b (patch)
tree58ec6d1969739a590e0c6c976bfebf04c8e9f31e /drivers/pci/probe.c
parent657472e9ccd9fccb82b775eb691c4b25b27451da (diff)
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 <shaohua.li@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/pci/probe.c')
-rw-r--r--drivers/pci/probe.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 07d5c7424b0..284ef392c3e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -9,6 +9,7 @@
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/cpumask.h>
+#include <linux/pci-aspm.h>
#include "pci.h"
#define CARDBUS_LATENCY_TIMER 176 /* secondary latency timer */
@@ -1014,6 +1015,10 @@ int pci_scan_slot(struct pci_bus *bus, int devfn)
break;
}
}
+
+ if (bus->self)
+ pcie_aspm_init_link_state(bus->self);
+
return nr;
}