What is the global architecture of Linux power management?

Linux is widely used in the field of consumer electronics, and power saving is an important issue for consumer electronics products. Below is the global architecture of power management.

Linux power management is very complex, involving system-level standby, frequency and voltage conversion, system idle processing, as well as each device driver's support for system standby and the runtime power management of each device. It can be said that it is related to every device in the system. Device drivers are closely related.

For consumer electronics, power management is very important. Therefore, this part of the work often occupies a considerable proportion in the development cycle. Figure 1 presents the overall architecture of Linux kernel power management. It can generally be summarized into the following categories:

1. CPUFreq, which dynamically converts voltage and frequency according to the system load when the CPU is running

2. When the system is idle, the CPU performs CPUIdle in low power consumption mode according to the idle situation.

3. CPU hot-plug support in multi-core systems

4. PM QoS applied for by systems and devices with special requirements for delay, which will act on the specific policy of CPUIdle

5. The device driver provides a series of entry functions for the system Suspend to RAM/Disk.

6. SoC enters the suspend state and SDRAM self-refresh entrance

7. Dynamic power management of the device's runtime, dynamically switching the device on and off based on usage

8. The underlying clock, voltage regulator, frequency/voltmeter (completed by OPP module) support, which may be used by each drive subsystem

Figure 1 Linux power management system architecture