The PCIe defined four link power state levels that are software controlled: fully active state (L0), electrical idle or standby state (L0s), L1 (lower power standby/slumber state), L2 (low power sleep ...

An “L0s” state was also defined in which each direction of the PCI Express link could be shut down independently with a quick resumption to normal operation. Fully active devices in “D0 ...