linux-kernel - Re: [PATCH v2 2/4] arm64: dts: allwinner: h6: Add cooling map for GPU

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Message-ID: <CAJiuCcfF=1Ob1oGABtHhM88m0LST727h88fXqCKYBiWRsYmtnA@mail.gmail.com>
Date:   Sat, 27 Aug 2022 18:49:56 +0200
From:   Clément Péron <peron.clem@...il.com>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-sunxi@...ts.linux.dev,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] arm64: dts: allwinner: h6: Add cooling map for GPU

Hi Samuel,

On Tue, 23 Aug 2022 at 05:16, Samuel Holland <samuel@...lland.org> wrote:
>
> On 8/21/22 12:30 PM, Clément Péron wrote:
> > Add a simple cooling map for the GPU.
>
> It would be good to document where the trip point temperatures came from.

If I remember correctly, I got those when getting the dtb from my
Beelink GS1 when it was running vendor Android with the oldest
Allwinner kernel.

But now that you ask I double check with the "new" vendor kernel source:
https://github.com/Allwinner-Homlet/H6-BSP4.9-linux/blob/master/arch/arm64/boot/dts/sunxi/sun50iw6p1.dtsi#L2034-L2053

And It's different from what I got in the past.
The throttling starts when the GPU is already very hot (95, 100 and
105°C) and seems to only disable the highest frequency (756, 624 and
576MHz).
Which let the GPU running at 0.91V @ 540MHz.

Which is far to be the lowest possible consumption for the GPU (0.81V
@ 336MHz would be better in the hottest situation)

I'm not an expert but either I could just try to copy/paste the same
behavior or try to have a more smooth cooling map (70, 85, 100°C).

What do you think?

Thanks,
Clement



>
> > Signed-off-by: Clément Péron <peron.clem@...il.com>
>
> Acked-by: Samuel Holland <samuel@...lland.org>
>
> > ---
> >  arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi | 22 ++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi b/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
> > index 5a28303d3d4c..943ae5374dd6 100644
> > --- a/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
> > +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
> > @@ -186,6 +186,7 @@ gpu: gpu@...0000 {
> >                       clocks = <&ccu CLK_GPU>, <&ccu CLK_BUS_GPU>;
> >                       clock-names = "core", "bus";
> >                       resets = <&ccu RST_BUS_GPU>;
> > +                     #cooling-cells = <2>;
> >                       status = "disabled";
> >               };
> >
> > @@ -1075,6 +1076,27 @@ gpu-thermal {
> >                       polling-delay-passive = <0>;
> >                       polling-delay = <0>;
> >                       thermal-sensors = <&ths 1>;
> > +
> > +                     trips {
> > +                             gpu_alert: gpu-alert {
> > +                                     temperature = <85000>;
> > +                                     hysteresis = <2000>;
> > +                                     type = "passive";
> > +                             };
> > +
> > +                             gpu-crit {
> > +                                     temperature = <100000>;
> > +                                     hysteresis = <0>;
> > +                                     type = "critical";
> > +                             };
> > +                     };
> > +
> > +                     cooling-maps {
> > +                             map0 {
> > +                                     trip = <&gpu_alert>;
> > +                                     cooling-device = <&gpu THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
> > +                             };
> > +                     };
> >               };
> >       };
> >  };
> >
>