SoC power governor: frequency scaling, thermal throttle, brownout recovery, gating (PC_ENABLE_POWER_MGMT). More...

#include "protocore_config.h"
#include <stddef.h>
#include <stdint.h>

Detailed Description

SoC power governor: frequency scaling, thermal throttle, brownout recovery, gating (PC_ENABLE_POWER_MGMT).

services/system/radio_power owns the radio and services/system/sleep_sched decides how long to sleep. Neither owns the SoC itself, which is where the rest of the power budget goes: the CPU clock, the die temperature, and the peripherals nobody is using.

The governor answers one question - given the current load, die temperature, and how the board last reset, what should the CPU clock be right now:

Scaling. Busy work runs at the ceiling; an idle server drops to the floor. Running a 240 MHz core to poll an idle socket is the single easiest power win on this part.
Thermal throttle. Hot parts clock down, and the restore threshold is lower than the throttle threshold. Without that gap a device sitting exactly at the limit oscillates between full speed and floor forever, which is worse than either.
Brownout recovery. A board that just browned out is on a supply that could not hold up the last load it saw, so slamming straight back to full speed invites the same collapse and a boot loop. After a brownout reset it comes up at the floor and stays there for a settle window.
Gating. Blocks the firmware never uses still burn current; Bluetooth is the big one, since the controller draws power whether or not anything is connected.

The decision is pure and takes every input explicitly - load, temperature, the brownout flag, the time since boot, and the previous throttle state for the hysteresis - so the whole governor is host-testable with no hardware. The binding only reads the sensors and applies the result.

Author: Douglas Quigg (dstroy0)

Date: 2026

Definition in file power_mgmt.h.