armv8 DVFS

DVFS Definition
The full text is ：Dynamic voltage and frequency scaling, Short for DVFS; Dynamic voltage frequency regulation

armv8 above CPU Such as CORTEX-A37 53 55 etc. V8 Architecturally CPU, The dominant frequency is relatively high , If it's always high , So waste electricity , Especially battery devices such as mobile phones , Flat .
At present, Ruixin micro , Full ambition ,AMLOGIC SOC All have this function

DVFS System flow ：

1. Collect signals related to system load , Calculate the current system load .
2. 2. According to the current load of the system , Predict the performance of the system in the next period .
3. 3. Convert the predicted performance into the required frequency , So as to adjust the clock setting of the chip . 4. Calculate the corresponding voltage according to the new frequency . Inform the power management module to adjust to CPU The voltage of .
4. in addition , When adjusting frequency and voltage , Pay special attention to the order of adjustment .
5. When the frequency is adjusted from high to low , You should reduce the frequency first , Lower the voltage again ; contrary , When the frequency is increased , The voltage should be increased first , Raise the frequency again .

Do it DVFS Not many , Because many of them are baffled by prediction algorithms , But the author believes that , With the progress of prediction algorithm ,DVFS Technology will be widely used , Because it can save a lot of energy . And energy saving for many portable devices , Often the first requirement .

problem ： FM only , Do not adjust the pressure ？

answer ： Tolerable , Especially in the commissioning stage .