linux-kernel - Re: [PATCH 1/2] arm64: dts: qcom: sc7180: Add gpu cooling support

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Date:   Fri, 9 Oct 2020 09:57:05 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Akhil P Oommen <akhilpo@...eaurora.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        Rob Herring <robh@...nel.org>, Rob Clark <robdclark@...il.com>,
        dri-devel@...edesktop.org,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jordan Crouse <jcrouse@...eaurora.org>
Subject: Re: [PATCH 1/2] arm64: dts: qcom: sc7180: Add gpu cooling support

On Fri, Oct 09, 2020 at 08:05:10AM -0700, Doug Anderson wrote:
> Hi,
> 
> On Thu, Oct 8, 2020 at 10:10 AM Akhil P Oommen <akhilpo@...eaurora.org> wrote:
> >
> > Add cooling-cells property and the cooling maps for the gpu tzones
> > to support GPU cooling.
> >
> > Signed-off-by: Akhil P Oommen <akhilpo@...eaurora.org>
> > ---
> >  arch/arm64/boot/dts/qcom/sc7180.dtsi | 29 ++++++++++++++++++++++-------
> >  1 file changed, 22 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> > index d46b383..40d6a28 100644
> > --- a/arch/arm64/boot/dts/qcom/sc7180.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> > @@ -2,7 +2,7 @@
> >  /*
> >   * SC7180 SoC device tree source
> >   *
> > - * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> > + * Copyright (c) 2019-20, The Linux Foundation. All rights reserved.
> >   */
> >
> >  #include <dt-bindings/clock/qcom,dispcc-sc7180.h>
> > @@ -1885,6 +1885,7 @@
> >                         iommus = <&adreno_smmu 0>;
> >                         operating-points-v2 = <&gpu_opp_table>;
> >                         qcom,gmu = <&gmu>;
> > +                       #cooling-cells = <2>;
> 
> Presumably we should add this to the devicetree bindings, too?
> 
> 
> >                         interconnects = <&gem_noc MASTER_GFX3D &mc_virt SLAVE_EBI1>;
> >                         interconnect-names = "gfx-mem";
> > @@ -3825,16 +3826,16 @@
> >                 };
> >
> >                 gpuss0-thermal {
> > -                       polling-delay-passive = <0>;
> > +                       polling-delay-passive = <100>;
> 
> Why did you make this change?  I'm pretty sure that we _don't_ want
> this since we're using interrupts for the thermal sensor.  See commit
> 22337b91022d ("arm64: dts: qcom: sc7180: Changed polling mode in
> Thermal-zones node").

I was going to ask the same, this shouldn't be needed.

> >                         polling-delay = <0>;
> >
> >                         thermal-sensors = <&tsens0 13>;
> >
> >                         trips {
> >                                 gpuss0_alert0: trip-point0 {
> > -                                       temperature = <90000>;
> > +                                       temperature = <95000>;
> >                                         hysteresis = <2000>;
> > -                                       type = "hot";
> > +                                       type = "passive";
> 
> Matthias probably knows better, but I wonder if we should be making
> two passive trip levels like we do with CPU.  IIRC this is important
> if someone wants to be able to use this with IPA.

Yes, please introduce a second trip point and make both of them
'passive'.