Hi Maxime, On Mon, 6 Apr 2020 at 10:10, Maxime Ripard <maxime@xxxxxxxxxx> wrote: > > Hi, > > On Sun, Apr 05, 2020 at 07:35:54PM +0200, Clément Péron wrote: > > Now that required drivers are merged we can contibute on DVFS > > support for Allwinner H6. > > > > This serie is based on Yangtao Li serie[0] and Ondřej Jirman work[1]. > > > > Most of the OPP tables are taken from original vendor kernel[2]. > > Plus there is a new CPU frequencies at 1.6GHz, 1.7GHz and 1.8GHz. > > > > I wrote a simple script to randomly set a frequency during > > a random time[3]. > > If you ever need to do that ever again, cpufreq-ljt-stress-test (found > here https://github.com/ssvb/cpuburn-arm) has proven to be very > reliable to detect cpufreq related issues. stress-ng might not be > enough since the (at least older) Allwinner SoCs tend to create cache > corruption when undervolted, and that might not be unnoticed by > stress-ng but will be catched by cpufreq-ljt-stress-test. Thanks for the tool and explanation. I will test the v3 with this one. > > Also, it will test each frequency, while random frequencies might skip > a few. I didn't count them but there was more than 2000lines, probability to miss a frequency is really low. Also changing from 500MHz to 1.8GHz could have trigger some out-of-spec issue. But just to be sure I will add an init phase before doing random stuff. > > > With this script and using stress-ng during several hours, I didn't > > see any issue. Moreover I have tested specifically the 1.8GHz on my > > Beelink GS1, max thermal 85°C is reached very quickly and then the > > SoC oscillates quickly between 1.5 and 1.8GHz. So i have added > > 1.6GHz and 1.7GHz my board now oscillate slower between 1.5GHz and > > 1.6GHz swapping every second and temperature is also morestable. > > > > I also test that that offlining CPU0 and doing DVFS on other CPUs > > works. As CPU regulator is only set for CPU0. > > > > But maybe it doesn't cost much to set the regulator for all the CPUs? > > > > Jernej test the GPU devfreq on several H6 board particulary the > > Tanix TX6 which doesn't have a proper dedicated PMIC and doesn't > > had any trouble with it. > > > > Do you think I can enable GPU OPP for all H6 Boards? > > It seems you're doing it? No I don't, see my answer on patch 4/7. Thanks for your review, Clément > > Maxime
