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

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Date:   Fri, 9 Oct 2020 08:05:10 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Akhil P Oommen <akhilpo@...eaurora.org>
Cc:     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>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: Re: [PATCH 1/2] arm64: dts: qcom: sc7180: Add gpu cooling support

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").


>                         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.