linux-kernel - Re: [PATCH v2 1/3] arm64: dts: qcom: sc7180: lazor: Simplify disabling of charger thermal zone

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Date:   Mon, 15 Mar 2021 14:48:46 -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>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] arm64: dts: qcom: sc7180: lazor: Simplify
 disabling of charger thermal zone

Hi,

On Fri, Mar 12, 2021 at 10:32 AM Matthias Kaehlcke <mka@...omium.org> wrote:
>
> Commit f73558cc83d1 ("arm64: dts: qcom: sc7180: Disable charger
> thermal zone for lazor") disables the charger thermal zone for
> specific lazor revisions due to an unsupported thermistor type.
> The initial idea was to disable the thermal zone for older
> revisions and leave it enabled for newer ones that use a
> supported thermistor. Finally the thermistor won't be changed
> on newer revisions, hence the thermal zone should be disabled
> for all lazor (and limozeen) revisions. Instead of disabling
> it per revision do it once in the shared .dtsi for lazor.
>
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>
> Changes in v2:
> - none
>
>  arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r0.dts | 9 ---------
>  arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r1.dts | 9 ---------
>  arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r3.dts | 9 ---------
>  arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor.dtsi   | 9 +++++++++
>  4 files changed, 9 insertions(+), 27 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r0.dts b/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r0.dts
> index 5c997cd90069..30e3e769d2b4 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r0.dts
> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r0.dts
> @@ -14,15 +14,6 @@ / {
>         compatible = "google,lazor-rev0", "qcom,sc7180";
>  };
>
> -/*
> - * Lazor is stuffed with a 47k NTC as charger thermistor which currently is
> - * not supported by the PM6150 ADC driver. Disable the charger thermal zone
> - * to avoid using bogus temperature values.
> - */
> -&charger_thermal {
> -       status = "disabled";
> -};
> -
>  &pp3300_hub {
>         /* pp3300_l7c is used to power the USB hub */
>         /delete-property/regulator-always-on;
> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r1.dts b/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r1.dts
> index d9fbcc7bc5bd..c2ef06367baf 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r1.dts
> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r1.dts
> @@ -14,15 +14,6 @@ / {
>         compatible = "google,lazor-rev1", "google,lazor-rev2", "qcom,sc7180";
>  };
>
> -/*
> - * Lazor is stuffed with a 47k NTC as charger thermistor which currently is
> - * not supported by the PM6150 ADC driver. Disable the charger thermal zone
> - * to avoid using bogus temperature values.
> - */
> -&charger_thermal {
> -       status = "disabled";
> -};
> -
>  &pp3300_hub {
>         /* pp3300_l7c is used to power the USB hub */
>         /delete-property/regulator-always-on;
> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r3.dts b/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r3.dts
> index ea8c2ee09741..b474df47cd70 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r3.dts
> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r3.dts
> @@ -14,12 +14,3 @@ / {
>         model = "Google Lazor (rev3+)";
>         compatible = "google,lazor", "qcom,sc7180";
>  };
> -
> -/*
> - * Lazor is stuffed with a 47k NTC as charger thermistor which currently is
> - * not supported by the PM6150 ADC driver. Disable the charger thermal zone
> - * to avoid using bogus temperature values.
> - */
> -&charger_thermal {
> -       status = "disabled";
> -};
> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor.dtsi
> index 6b10b96173e8..6d540321b4a5 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor.dtsi
> @@ -41,6 +41,15 @@ ap_ts: touchscreen@10 {
>         };
>  };
>
> +/*
> + * Lazor is stuffed with a 47k NTC as charger thermistor which currently is
> + * not supported by the PM6150 ADC driver. Disable the charger thermal zone
> + * to avoid using bogus temperature values.
> + */
> +&charger_thermal {
> +       status = "disabled";
> +};

So this always confuses me too, but the sort order is wrong.  :(

While it _looks_like the node above you is "ap_ts", I believe the
convention for sorting is not to use labels added in this file. Yeah,
we gotta document this somewhere. Thus, this node should be sorted as
"charger_thermal" (using a label not defined in this file) and the
node above should be sorted as "touchscreen@10" and thus we should go
above it.

In general I think the reason we tend to use the node name and not any
labels is that it keeps us from having to redo the sort ordering if we
give something a new label. It also helps keep the i2c busses
together, the SPI busses together, etc.

That's just a sort order nit, though, so:

Reviewed-by: Douglas Anderson <dianders@...omium.org>


-Doug