Re: [PATCH 3/3] arm64: dts: rockchip: set rk3399 dynamic CPU power coefficients

Brian Norris
2017-06-23T18:50:07Z

On Fri, Jun 23, 2017 at 08:39:25PM +0200, Heiko Stuebner wrote:
> Am Freitag, 23. Juni 2017, 10:07:37 CEST schrieb Brian Norris:
> > Provide the dynamic power coefficient of the big and little CPU
> > clusters. These numbers are currently in use on the Samsung Chromebook
> > Plus ("Kevin").
> >
> > The power allocator thermal governor doesn't know how to do anything if
> > it doesn't get power parameters from its cooling devices (in this case,
> > CPUfreq). So this effectively enables the power-allocator governor.
> >
> > Signed-off-by: Brian Norris <briannorris@chromium.org>
> > ---
> > arch/arm64/boot/dts/rockchip/rk3399.dtsi | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > index 69c56f7316c4..4f6667547814 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > @@ -109,6 +109,7 @@
> > reg = <0x0 0x0>;
> > enable-method = "psci";
> > #cooling-cells = <2>; /* min followed by max */
> > + dynamic-power-coefficient = <100>;
> > clocks = <&cru ARMCLKL>;
> > };
> >
> > @@ -142,6 +143,7 @@
> > reg = <0x0 0x100>;
> > enable-method = "psci";
> > #cooling-cells = <2>; /* min followed by max */
> > + dynamic-power-coefficient = <100>;
> > clocks = <&cru ARMCLKB>;
> > };
> >
> >
>
> I think these should be set for all cores, similar to clocks. While
> cpufreq and friends regularly only take the first number, in a
> hw-description sense, it should be part of every core in the dt.

It's kinda paired with the cooling information (e.g., #cooling-cells)
which are only present in the first CPU in the cluster, currently.

I can copy this definitely real, empirical value into the other CPUs if
you really think that's necessary :)

Brian