Re: [PATCHv1 0/3] Odroid c2 missing regulator linking

Anand Moon
2019-08-30T09:34:47Z

Hi Neil,

On Fri, 30 Aug 2019 at 13:01, Neil Armstrong <narmstrong@baylibre.com> wrote:
>
> On 29/08/2019 20:35, Anand Moon wrote:
> > Hi Neil,
> >
> > On Thu, 29 Aug 2019 at 13:58, Neil Armstrong <narmstrong@baylibre.com> 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@baylibre.com>
> >>
> >
> > 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