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| author | Shaohua Li <shaohua.li@intel.com> | 2008-02-25 09:46:41 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-04-20 21:47:03 -0700 |
| commit | 7d715a6c1ae5785d00fb9a876b5abdfc43abc44b (patch) | |
| tree | 58ec6d1969739a590e0c6c976bfebf04c8e9f31e /include/linux/pci_regs.h | |
| parent | 657472e9ccd9fccb82b775eb691c4b25b27451da (diff) | |
| download | op-kernel-dev-7d715a6c1ae5785d00fb9a876b5abdfc43abc44b.zip op-kernel-dev-7d715a6c1ae5785d00fb9a876b5abdfc43abc44b.tar.gz | |
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 'include/linux/pci_regs.h')
| -rw-r--r-- | include/linux/pci_regs.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h index c1914a8..c0c1223 100644 --- a/include/linux/pci_regs.h +++ b/include/linux/pci_regs.h @@ -395,9 +395,17 @@ #define PCI_EXP_DEVSTA_AUXPD 0x10 /* AUX Power Detected */ #define PCI_EXP_DEVSTA_TRPND 0x20 /* Transactions Pending */ #define PCI_EXP_LNKCAP 12 /* Link Capabilities */ +#define PCI_EXP_LNKCAP_ASPMS 0xc00 /* ASPM Support */ +#define PCI_EXP_LNKCAP_L0SEL 0x7000 /* L0s Exit Latency */ +#define PCI_EXP_LNKCAP_L1EL 0x38000 /* L1 Exit Latency */ +#define PCI_EXP_LNKCAP_CLKPM 0x40000 /* L1 Clock Power Management */ #define PCI_EXP_LNKCTL 16 /* Link Control */ +#define PCI_EXP_LNKCTL_RL 0x20 /* Retrain Link */ +#define PCI_EXP_LNKCTL_CCC 0x40 /* Common Clock COnfiguration */ #define PCI_EXP_LNKCTL_CLKREQ_EN 0x100 /* Enable clkreq */ #define PCI_EXP_LNKSTA 18 /* Link Status */ +#define PCI_EXP_LNKSTA_LT 0x800 /* Link Training */ +#define PCI_EXP_LNKSTA_SLC 0x1000 /* Slot Clock Configuration */ #define PCI_EXP_SLTCAP 20 /* Slot Capabilities */ #define PCI_EXP_SLTCTL 24 /* Slot Control */ #define PCI_EXP_SLTSTA 26 /* Slot Status */ |
