The undervolt opp table is borrowed from rk3399-gru the google devicetree. Nothing dramatic, but undervolts most operating points compared to stock opp table.
Also enable the memory controller to dynamically schedule ddr memory frequencies. Stock is fixed 856MHz, now it supports 328MHz, 416MHz, 666MHz and 856MHz.
The scheduler is fine-tuned a bit so that it is more eager to scale up – stock version tends to almost always run at 328MHz, even under heavy load, which indeed has an impact on the performance – about 15% lower Geekbench scores.
After tuning, the statistics looks more healthy:
yatli@devterm /sys/class/devfreq/memory-controller % cat trans_stat
From : To
: 328000000 416000000 666000000 856000000 time(ms)
* 328000000: 0 0 0 2772 14605110
416000000: 538 0 0 231 385320
666000000: 508 164 0 63 376450
856000000: 1727 605 735 0 1723200
Total transition : 7343
Tested, can feel the temperature going down.
Even performs better at Geekbench, possibly due to less thermal throttling: N/A - Geekbench Browser
Update: when undervolt meets suspend, need this patch: kernel: add suspend opp to prevent overvoltage · yatli/arch-linux-arm-clockworkpi-a06@d7f456b · GitHub
… otherwise rk808 may pass out (by jumping from undervolted 800mV to default 1000mV)
