config ARCH_HAS_DEVFREQ bool depends on ARCH_HAS_OPP help Denotes that the architecture supports DEVFREQ. If the architecture supports multiple OPP entries per device and the frequency of the devices with OPPs may be altered dynamically, the architecture supports DEVFREQ. menuconfig PM_DEVFREQ bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support" depends on PM_OPP && ARCH_HAS_DEVFREQ help With OPP support, a device may have a list of frequencies and voltages available. DEVFREQ, a generic DVFS framework can be registered for a device with OPP support in order to let the governor provided to DEVFREQ choose an operating frequency based on the OPP's list and the policy given with DEVFREQ. Each device may have its own governor and policy. DEVFREQ can reevaluate the device state periodically and/or based on the OPP list changes (each frequency/voltage pair in OPP may be disabled or enabled). Like some CPUs with CPUFREQ, a device may have multiple clocks. However, because the clock frequencies of a single device are determined by the single device's state, an instance of DEVFREQ is attached to a single device and returns a "representative" clock frequency from the OPP of the device, which is also attached to a device by 1-to-1. The device registering DEVFREQ takes the responsiblity to "interpret" the frequency listed in OPP and to set its every clock accordingly with the "target" callback given to DEVFREQ. if PM_DEVFREQ comment "DEVFREQ Drivers" endif # PM_DEVFREQ