in char/bbc_envctrl.c [354:388]
static int maybe_new_cpu_fan_speed(struct bbc_fan_control *fp)
{
enum fan_action decision = prioritize_fan_action(FAN_CPU);
int ret;
if (decision == FAN_SAME)
return 0;
ret = 1;
if (decision == FAN_FULLBLAST) {
if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
ret = 0;
else
fp->cpu_fan_speed = FAN_SPEED_MAX;
} else {
if (decision == FAN_FASTER) {
if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
ret = 0;
else {
fp->cpu_fan_speed += 2;
if (fp->system_fan_speed <
(fp->cpu_fan_speed - 3))
fp->system_fan_speed =
fp->cpu_fan_speed - 3;
}
} else {
if (fp->cpu_fan_speed <= FAN_SPEED_MIN)
ret = 0;
else
fp->cpu_fan_speed -= 1;
}
}
return ret;
}