linux-kernel - Re: [PATCH 3/3] arm64: dts: qcom: pm8998: Add thermal zone

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Date:   Thu, 28 Jun 2018 15:58:41 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-soc@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        David Collins <collinsd@...eaurora.org>,
        Stephen Boyd <sboyd@...nel.org>
Subject: Re: [PATCH 3/3] arm64: dts: qcom: pm8998: Add thermal zone

Hi,

On Thu, Jun 28, 2018 at 2:09 PM, Matthias Kaehlcke <mka@...omium.org> wrote:
> Add pm8998 thermal zone based on the examples in the spmi-temp-alarm
> bindings.
>
> Note: devices with the pm8998 need to have a 'thermal-zones' node (which
> may be empty) with a label 'thermal_zones'.
>
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>  arch/arm64/boot/dts/qcom/pm8998.dtsi | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)

Do you know if this patch actually does anything since you didn't
define a cooling-maps?  Hopefully at least the critical shuts things
down?

Do you have any idea how we'll eventually want to specify a
cooling-maps?  Are we just going to assume we're included by an sdm845
device and refer to the big/little CPU phandles?


> diff --git a/arch/arm64/boot/dts/qcom/pm8998.dtsi b/arch/arm64/boot/dts/qcom/pm8998.dtsi
> index f2d39074ed74..d85ceb4f976b 100644
> --- a/arch/arm64/boot/dts/qcom/pm8998.dtsi
> +++ b/arch/arm64/boot/dts/qcom/pm8998.dtsi
> @@ -3,6 +3,7 @@
>
>  #include <dt-bindings/spmi/spmi.h>
>  #include <dt-bindings/interrupt-controller/irq.h>
> +#include <dt-bindings/thermal/thermal.h>
>
>  &spmi_bus {
>         pm8998_lsid0: pmic@0 {
> @@ -59,3 +60,30 @@
>                 #size-cells = <0>;
>         };
>  };
> +
> +&thermal_zones {

As per comments in patch #1, don't rely on a label.  Just put your
stuff in a top-level "thermal-zones" node.

> +       pm8998 {
> +               polling-delay-passive = <250>;
> +               polling-delay = <1000>;
> +
> +               thermal-sensors = <&pm8998_temp>;
> +
> +               trips {
> +                       passive {

IMO you should proactively put a label on these trips even if there's
no cooling device yet.  It's expected that at some point someone will
add a cooling device and refer to them, right?



-Doug