Intelligent sequence type small computer system interface physical layer power management

Abstract

The present disclosure generally relates to a method for intelligent device initiated SAS Phy PM. Using device internal phy characteristics and future phy usage queue, the device determines optimal SAS Phy PM usage based on a predetermined configuration preference of power versus performance. The device achieves optimal SAS Phy PM Usage by implementing a state machine to manage phy PM states and transitions between the PM states. The device state machine includes capabilities to proactively initiate transitions to partial or slumber PM states, start early wake-up from partial or slumber PM states to mask the associated latency impacts of exiting partial or slumber PM states, and selectively reject host requests to enter a partial or slumber PM state.

Description

technical field [0001] Embodiments of the present disclosure generally relate to SAS (Serial Attached Small Computer System Interface, serial small computer system interface) phy (physical layer) power management (PM) for smart device initiation. Background technique [0002] The host computing device communicates with the storage device through ports on the storage device. A port consists of one or more physical layers, known as phy. The physical layer is the circuit that implements the physical layer functions. For storage devices using a SAS interface, narrow ports have a single phy and wide ports have two or more phys. The physical layer is physically coupled to other phys through physical links such as fiber optic or copper cables. The phy performs various functions on various signals received over the physical link of that port. [0003] The host device does not have any visibility into the timing or selection of phy usage by a particular device in a wide port. Ty...

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Problems solved by technology

[0004] With wide ports, it could easily be the case that the phy sending the initial signal is not the best phy to handle the requested operation

Additionally, there are multiple operations that may need to be performed, and thus the storage device may not be operating at peak efficiency if the same phy that received the initial signal is also processing the requested operation

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