BKK19-119 - Device power management and idle

Session Abstract

It can be a rather complicated task to deploy optimized power management (PM) support in a driver in Linux. There are several PM frameworks and corresponding function callbacks available per device, which the driver developer needs detailed knowledge about. Particularly, when the goal is to reach the best energy efficient behavior.

Additionally, ARM SoCs in general, have quite sophisticated and fine grained methods to put parts of a silicon into a low power state, as to avoid wasting power when there are no active users of these parts. In Linux these parts are typically modeled as so called, PM domains.

During the session, we dive into some of the relevant PM frameworks for dealing with idle and explains the concepts behind them. We look into how to deploy support for system wide low power states, such as suspend to ram, suspend to idle and suspend to disk. We look at it, both from the PM domain and the driver point of view.

Moreover, to deploy fine grained PM support, the session gives some best practices of how to use runtime PM and the generic PM domain frameworks, as well as looks into how to implement support for called wakeup interrupts.

Session Speakers

Ulf Hansson

Senior Kernel Engineer (Linaro)

Ulf has a very long experience of using Linux and has been contributing the Linux kernel development for many years by now. He maintains the MMC subsystem and the generic PM domain in the Linux kernel, but also spends lots of time reviewing various changes related to power management and to their corresponding frameworks.

Moreover, Ulf has a background in real-time and embedded systems. He also has an in-depth knowledge about flash memory technologies, such as NAND and NOR.

Ulf is working for Linaro and specializing in power management.

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