Hi Neil / Kevin, On Tue, 10 Dec 2019 at 14:13, Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote: > > On 09/12/2019 23:12, Kevin Hilman wrote: > > Anand Moon <linux.amoon@xxxxxxxxx> writes: > > > >> Some how this patch got lost, so resend this again. > >> > >> [0] https://patchwork.kernel.org/patch/11136545/ > >> > >> This patch enable DVFS on GXBB Odroid C2. > >> > >> DVFS has been tested by running the arm64 cpuburn > >> [1] https://github.com/ssvb/cpuburn-arm/blob/master/cpuburn-a53.S > >> PM-QA testing > >> [2] https://git.linaro.org/power/pm-qa.git [cpufreq testcase] > >> > >> Tested on latest U-Boot 2019.07-1 (Aug 01 2019 - 23:58:01 +0000) Arch Linux ARM > > > > Have you tested with the Harkernel u-boot? > > > > Last I remember, enabling CPUfreq will cause system hangs with the > > Hardkernel u-boot because of improperly enabled frequencies, so I'm not > > terribly inclined to merge this patch. HK u-boot have many issue with loading the kernel, with load address *it's really hard to build the kernel for HK u-boot*, to get the configuration correctly. Well I have tested with mainline u-boot with latest ATF . I would prefer mainline u-boot for all the Amlogic SBC, since they sync with latest driver changes. > > Same, since the bootloader boots with the max supported freq of the board, > there is not real need of DVFS except for specific low-power use-cases. > > And still, some early boards still use the bad SCPI freq table, we can't break them. > > Neil > I will leave this to your expert domain knowledge if you want to enable this now. Here is output of on the latest kernel. *cpupower* # cpupower frequency-info analyzing CPU 0: driver: scpi-cpufreq CPUs which run at the same hardware frequency: 0 1 2 3 CPUs which need to have their frequency coordinated by software: 0 1 2 3 maximum transition latency: 200 us hardware limits: 100.0 MHz - 1.54 GHz available frequency steps: 100.0 MHz, 250 MHz, 500 MHz, 1000 MHz, 1.30 GHz, 1.54 GHz available cpufreq governors: conservative ondemand userspace powersave performance schedutil current policy: frequency should be within 100.0 MHz and 100.0 MHz. The governor "ondemand" may decide which speed to use within this range. current CPU frequency: 100.0 MHz (asserted by call to hardware) *powertop* # powertop Package | CPU 0 100 MHz 47.1% | 100 MHz 41.5% 250 MHz 0.0% | 250 MHz 0.0% 500 MHz 0.0% | 500 MHz 0.0% 1000 MHz 0.0% | 1000 MHz 0.0% 1296 MHz 0.0% | 1296 MHz 0.0% 1.54 GHz 0.0% | 1.54 GHz 0.0% Idle 52.9% | Idle 58.5% > > > >> Patch based on my next-20191031 for 5.5.x kernel. > >> Hope this is not late entry. > > > > Re: "too late". FYI... when you post things as RFC, it means you're > > looking for comments (Request For Comment) but that it's not intended > > for merging. Ok thanks for this input. > > > > I didn't see any comments on this, but I also didn't see a non-RFC > > follow-up, so I didn't queue it for v5.5. No problem. > > > > Kevin > > > -Anand
