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CONFIG_PM_DEVFREQ: Generic Dynamic Voltage and Frequency Scaling (DVFS) support

General informations

The Linux kernel configuration item CONFIG_PM_DEVFREQ:

Help text

A device may have a list of frequencies and voltages available. devfreq, a generic DVFS framework can be registered for a device in order to let the governor provided to devfreq choose an operating frequency based on the device driver's policy.

Each device may have its own governor and policy. Devfreq can reevaluate the device state periodically and/or based on the notification to "nb", a notifier block, of devfreq.

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 of the device, which is also attached to a device by 1-to-1. The device registering devfreq takes the responsibility to "interpret" the representative frequency and to set its every clock accordingly with the "target" callback given to devfreq.

When OPP is used with the devfreq device, it is recommended to register devfreq's nb to the OPP's notifier head. If OPP is used with the devfreq device, you may use OPP helper functions defined in devfreq.h.

Hardware

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