Disable ASPM on pre-1.1 PCIe devices, as many of them don't implement it
correctly.
Tested-by: NJack Howarth <howarth@bromo.msbb.uc.edu>
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

The ACPI FADT table includes an ASPM control bit. If the bit is set, do
not enable ASPM since it may indicate that the platform doesn't actually
support the feature.
Tested-by: NJack Howarth <howarth@bromo.msbb.uc.edu>
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

The Slot 03:00.* of JMicron controller has two functions, but one is
PCIE endpoint the other isn't PCIE device, very strange. PCIE spec
defines all functions should have the same config for ASPM, so disable
ASPM for the whole slot in this case.
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

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: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This reverts commit 6c723d5b.

It caused build errors on non-x86 platforms, config file confusion, and
even some boot errors on some x86-64 boxes.  All around, not quite ready
for prime-time :(

Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

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: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>