LinuxCon+ContainerCon Europe 2016

CPU frequency scaling is one of standard features implemented when adding new ARM platform support to Linux kernel. Most (if not all) recent ARM platforms are making use of the generic Device Tree based CPUfreq driver (cpufreq-dt). During This tutorial Bartlomiej will present the inner workings of the cpufreq-dt driver and will show all the steps (including mandatory Device Tree changes and optional clocks subsystem adjustments) needed to make the driver work on new ARM platform. Off-the-shelf Hardkernel's ODROID-XU3 board (which is Samsung Exynos5422 SoC based) will be used as the example hardware for showing the step-by-step implementation of CPU frequency scaling. The tutorial will end with discussion of advanced topics like how to enable software boost functionality, when to use generic ARM big.LITTLE CPUfreq driver and when there is a need to develop a new CPUfreq driver.