Re: Re: [PATCH v4 3/5] arm64: dts: allwinner: h6: Add GPU OPP table

[Jernej Škrabec]

Dne torek, 06. september 2022 ob 21:26:34 CEST je Clément Péron napisal(a):
> Hi Jernej,
> 
> On Tue, 6 Sept 2022 at 21:10, Jernej Škrabec <jernej.skrabec@xxxxxxxxx> 
wrote:
> > Dne torek, 06. september 2022 ob 17:30:32 CEST je Clément Péron 
napisal(a):
> > > Add an Operating Performance Points table for the GPU to
> > > enable Dynamic Voltage & Frequency Scaling on the H6.
> > > 
> > > The voltage range is set with minimal voltage set to the target
> > > and the maximal voltage set to 1.2V. This allow DVFS framework to
> > > work properly on board with fixed regulator.
> > > 
> > > Signed-off-by: Clément Péron <peron.clem@xxxxxxxxx>
> > > ---
> > > 
> > >  .../boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi | 87 +++++++++++++++++++
> > >  1 file changed, 87 insertions(+)
> > >  create mode 100644 arch/arm64/boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi
> > > 
> > > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi
> > > b/arch/arm64/boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi new file mode
> > > 100644
> > > index 000000000000..b48049c4fc85
> > > --- /dev/null
> > > +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-gpu-opp.dtsi
> > > @@ -0,0 +1,87 @@
> > > +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> > > +// Copyright (C) 2022 Clément Péron <peron.clem@xxxxxxxxx>
> > > +
> > > +/ {
> > > +     gpu_opp_table: opp-table-gpu {
> > > +             compatible = "operating-points-v2";
> > > +
> > > +             opp-216000000 {
> > > +                     opp-hz = /bits/ 64 <216000000>;
> > > +                     opp-microvolt = <810000 810000 1200000>;
> > > +             };
> > > +
> > > +             opp-264000000 {
> > > +                     opp-hz = /bits/ 64 <264000000>;
> > > +                     opp-microvolt = <810000 810000 1200000>;
> > > +             };
> > 
> > As mentioned in clock patch review, rates below 288 MHz are deemed
> > unstable on GPU PLL by vendor GPU kernel driver. At least in the BSP
> > version that I have. Did you test these points? If not, better to drop
> > them.
> 
> I changed the governor to userspace and set the freq to 216MHz / 264MHz
> Run glmark2 and didn't observe any glitch nor issue.
> 
> I'm not sure if it's enough to say it's stable but I didn't observe
> any strange behavior.

Ok then.

Forgot to ask, where did you get 1.2 V as an upper limit? H6 datasheet lists 
max. GPU voltage as 1.08 V.

Best regards,
Jernej

> 
> Regards,
> Clement
> 
> > Best regards,
> > Jernej
> > 
> > > +
> > > +             opp-312000000 {
> > > +                     opp-hz = /bits/ 64 <312000000>;
> > > +                     opp-microvolt = <810000 810000 1200000>;
> > > +             };
> > > +
> > > +             opp-336000000 {
> > > +                     opp-hz = /bits/ 64 <336000000>;
> > > +                     opp-microvolt = <810000 810000 1200000>;
> > > +             };
> > > +
> > > +             opp-360000000 {
> > > +                     opp-hz = /bits/ 64 <360000000>;
> > > +                     opp-microvolt = <820000 820000 1200000>;
> > > +             };
> > > +
> > > +             opp-384000000 {
> > > +                     opp-hz = /bits/ 64 <384000000>;
> > > +                     opp-microvolt = <830000 830000 1200000>;
> > > +             };
> > > +
> > > +             opp-408000000 {
> > > +                     opp-hz = /bits/ 64 <408000000>;
> > > +                     opp-microvolt = <840000 840000 1200000>;
> > > +             };
> > > +
> > > +             opp-420000000 {
> > > +                     opp-hz = /bits/ 64 <420000000>;
> > > +                     opp-microvolt = <850000 850000 1200000>;
> > > +             };
> > > +
> > > +             opp-432000000 {
> > > +                     opp-hz = /bits/ 64 <432000000>;
> > > +                     opp-microvolt = <860000 860000 1200000>;
> > > +             };
> > > +
> > > +             opp-456000000 {
> > > +                     opp-hz = /bits/ 64 <456000000>;
> > > +                     opp-microvolt = <870000 870000 1200000>;
> > > +             };
> > > +
> > > +             opp-504000000 {
> > > +                     opp-hz = /bits/ 64 <504000000>;
> > > +                     opp-microvolt = <890000 890000 1200000>;
> > > +             };
> > > +
> > > +             opp-540000000 {
> > > +                     opp-hz = /bits/ 64 <540000000>;
> > > +                     opp-microvolt = <910000 910000 1200000>;
> > > +             };
> > > +
> > > +             opp-576000000 {
> > > +                     opp-hz = /bits/ 64 <576000000>;
> > > +                     opp-microvolt = <930000 930000 1200000>;
> > > +             };
> > > +
> > > +             opp-624000000 {
> > > +                     opp-hz = /bits/ 64 <624000000>;
> > > +                     opp-microvolt = <950000 950000 1200000>;
> > > +             };
> > > +
> > > +             opp-756000000 {
> > > +                     opp-hz = /bits/ 64 <756000000>;
> > > +                     opp-microvolt = <1040000 1040000 1200000>;
> > > +             };
> > > +     };
> > > +};
> > > +
> > > +&gpu {
> > > +     operating-points-v2 = <&gpu_opp_table>;
> > > +};
> > > --
> > > 2.34.1