pci express architecture power management

This paper presents power management guidelines for PCI Express links on Intel-based Mobile platforms. It describes the mapping from platform sleeping states and device power states to link power states, including the procedure to support Mobile-specific S1/POS and CPU C3/C4 scenarios. Device and platform power saving opportunities are identified for each link power state. L1 entry policy is also recommended to optimize device power. Several power optimization techniques are described, including minimizing flow control updates and acknowledgement packets to improve bandwidth efficiency, and pipelining packets to increase opportunities for active state link power management. These power management guidelines enable architectural innovation to achieve power-optimized interconnect performance.