Power Management in Linux with a coprocessor

Shutting down the main processor of an SoC in the idle and standby state results in significant power savings. However, doing so requires the responsibility of reviving the system to be passed onto an independent entity in the system. Texas Instruments has taken the lead in introducing a novel approach for system power management in its AM335x processor family involving a Cortex-M3 to assist the main processor. In the future there will other devices from Texas Instruments and possibly other silicon vendors which adopt this technique.

Integrating a co-processor which is not running Linux with the PM framework comes with a new set of challenges. The co-processor needs to interact with the host processor for idle as well as standby power management. How do we communicate with a co-processor without significant overhead in the idle thread? In case the co-processor stops responding what should be recovery mechanism in the PM framework? What should be the mechanism for exporting the core details like the configured wakeup sources to the co-processor?

This session will focus on the above mentioned challenges and other issues surrounding the usage of a co-processor for power management in Linux.

Topic Lead: Vaibhav Bedia
Vaibhav Bedia, Software Systems Engineer, Texas Instruments, works on Linux kernel development for Sitara ARM microprocessors.