linux-kernel - Re: [PATCH] arm64: dts: qcom: pm6150: Add thermal zone for PMIC on-die temperature

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Message-ID: <CAD=FV=XcoLLCn+H6h9cX+qPjoueVFgK8BssvUXQ6WjVAapRyMg@mail.gmail.com>
Date:   Wed, 2 Jun 2021 09:36:07 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Stephen Boyd <swboyd@...omium.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] arm64: dts: qcom: pm6150: Add thermal zone for PMIC
 on-die temperature

Hi,

On Wed, Jun 2, 2021 at 9:06 AM Matthias Kaehlcke <mka@...omium.org> wrote:
>
> Add a thermal zone for the pm6150 on-die temperature. The system should
> try to shut down orderly when the temperature reaches 95degC, otherwise
> the PMIC will power off at 115degC.
>
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>
>  arch/arm64/boot/dts/qcom/pm6150.dtsi | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/qcom/pm6150.dtsi b/arch/arm64/boot/dts/qcom/pm6150.dtsi
> index 8ab4f1f78bbf..de7fb129f739 100644
> --- a/arch/arm64/boot/dts/qcom/pm6150.dtsi
> +++ b/arch/arm64/boot/dts/qcom/pm6150.dtsi
> @@ -7,6 +7,30 @@
>  #include <dt-bindings/spmi/spmi.h>
>  #include <dt-bindings/thermal/thermal.h>
>
> +/ {
> +       thermal-zones {
> +               pm6150_thermal: pm6150-thermal {
> +                       polling-delay-passive = <100>;
> +                       polling-delay = <0>;
> +                       thermal-sensors = <&pm6150_temp>;
> +
> +                       trips {
> +                               pm6150_trip0: trip0 {
> +                                       temperature = <95000>;
> +                                       hysteresis = <0>;
> +                                       type = "passive";
> +                               };
> +
> +                               pm6150_crit: pm6150-crit {

Nit that the node names are not symmetric. One is "trip0" and the
other is "pm6510-crit". Seems like you can remove the "pm6150-" prefix
from this one (but keep it in the label?)

> +                                       temperature = <115000>;
> +                                       hysteresis = <0>;
> +                                       type = "critical";
> +                               };
> +                       };
> +               };

Correct me if I'm misunderstanding, but I don't think that the
description of this patch matches the contents. You're saying that the
PMIC will power itself off at 115C and that we want to do an orderly
shutdown _before_ the PMIC powers off. Doesn't that mean that the
"critical" trip needs to be at some temperature _lower_ than 115C? As
I remember it the system performs an orderly shutdown starting when it
sees the critical temperature.

-Doug