Hi Neil, On Fri, 30 Aug 2019 at 13:01, Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote: > > On 29/08/2019 20:35, Anand Moon wrote: > > Hi Neil, > > > > On Thu, 29 Aug 2019 at 13:58, Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote: > >> > >> On 28/08/2019 22:27, Anand Moon wrote: > >>> Below small changes help re-configure or fix missing inter linking > >>> of regulator node. > >>> > >>> Changes based top on my prevoius series. > >> > >> For the serie: > >> Reviewed-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx> > >> > > > > Thanks for your review. > > > >>> > >>> [0] https://patchwork.kernel.org/cover/11113091/ > >>> > >>> TOOD: Add support for DVFS GXBB odroid board in next series. > >> > >> I'm curious how you will do this ! > > > > I was just studying you previous series on how you have implemented > > this feature for C1, N2 and VIM3 boards. > > > > [0] https://patchwork.kernel.org/cover/11114125/ > > > > I started gathering key inputs needed for this ie *clk / pwm* > > like VDDCPU and VDDE clk changes. > > > > But it looks like of the complex clk framework needed, so I leave this to the > > expert like your team of developers to do this much quick and efficiently. > > On GXBB, GXL, GXM and AXG SoCs, CPU Frequency setting and PWM Regulator setup is > done by the SCPI Co-processor via the SCPI protocol. > > Thus, we should not handle it from Linux, and even if we could, we don't have the > registers documentation of the CPU clusters clock tree. > Ok thanks. > SCPI works fine on all tested devices, except Odroid-C2, because Hardkernel left > the > 1.5GHz freq in the initial SCPI tables loaded by the BL2, i.e. packed with U-Boot. > Nowadays they have removed the bad frequencies, but still some devices uses the old > bootloader. > > But in the SCPI case we trust the table returned by the firmware and use it as-in, > and there is no (simple ?) way to override the table and set a max frequency. > > This is why we disabled SCPI. > > See https://patchwork.kernel.org/patch/9500175/ I have quickly enable this on my board and here the cpufreq info [alarm@alarm ~]$ 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 1.54 GHz. The governor "ondemand" may decide which speed to use within this range. current CPU frequency: Unable to call hardware current CPU frequency: 250 MHz (asserted by call to kernel) I did some simple stress testing and observed the freq scaling is working fine when cpufreq governor is set to ondemand. Powertop output. Package | CPU 0 100 MHz 5.2% | 100 MHz 1.6% 250 MHz 4.4% | 250 MHz 4.3% 500 MHz 2.6% | 500 MHz 2.4% 1000 MHz 0.5% | 1000 MHz 0.3% 1296 MHz 0.2% | 1296 MHz 0.1% 1.54 GHz 0.2% | 1.54 GHz 0.1% Idle 86.9% | Idle 91.2% Here the output on the linaro's pm-qa testing for cpufreq. [1] https://pastebin.com/h880WATn Almost all the test case pass with this one as off now. Best Regards -Anand
