PCI/ASPM: Add sysfs attributes for controlling ASPM link states
Add sysfs attributes to Endpoints and other Upstream Ports to control ASPM, Clock PM, and L1 PM Substates. The new attributes are: /sys/devices/pci*/.../link/clkpm /sys/devices/pci*/.../link/l0s_aspm /sys/devices/pci*/.../link/l1_aspm /sys/devices/pci*/.../link/l1_1_aspm /sys/devices/pci*/.../link/l1_2_aspm /sys/devices/pci*/.../link/l1_1_pcipm /sys/devices/pci*/.../link/l1_2_pcipm An attribute is only visible if both ends of the Link leading to the device support the state. Writing y/1/on to the file enables the state; n/0/off disables it. These attributes can be used to tune the power/performance tradeoff for individual devices. [bhelgaas: commit log, rename directory to "link"] Link: https://lore.kernel.org/r/b1c83f8a-9bf6-eac5-82d0-cf5b90128fbf@gmail.com Signed-off-by:Heiner Kallweit <hkallweit1@gmail.com> Signed-off-by: