linux-kernel - Re: [PATCH] arm64: dts: qcom: sc7180: Base homestar's power coefficients in reality

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Message-ID: <YU4X+QH2X00ah7Gh@google.com>
Date:   Fri, 24 Sep 2021 11:24:57 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>, devicetree@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: sc7180: Base homestar's power
 coefficients in reality

On Thu, Sep 23, 2021 at 08:14:04AM -0700, Douglas Anderson wrote:
> The commit 82ea7d411d43 ("arm64: dts: qcom: sc7180: Base dynamic CPU
> power coefficients in reality") and the commit be0416a3f917 ("arm64:
> dts: qcom: Add sc7180-trogdor-homestar") passed each other in the
> tubes that make up the Internet. Despite the fact the patches didn't
> cause a merge conflict, they need to account for each other. Do that.
> 
> Fixes: 82ea7d411d43 ("arm64: dts: qcom: sc7180: Base dynamic CPU power coefficients in reality")
> Fixes: be0416a3f917 ("arm64: dts: qcom: Add sc7180-trogdor-homestar")
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
>
>  arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
> index cd3054226865..382f8c6f1576 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
> @@ -51,7 +51,7 @@ skin_temp_thermal: skin-temp-thermal {
>  			polling-delay = <0>;
>  
>  			thermal-sensors = <&pm6150_adc_tm 1>;
> -			sustainable-power = <814>;
> +			sustainable-power = <965>;

Just as a note: the original values corresponded to the modelled power
consumption of two big cores at 1.55 GHz. The value was based on
'/sys/kernel/debug/energy_model/pd6/cs:1555200/power' and multiplied
by two. So the new values could be determined in the same manner.

In any case these values are approximations, it's not really important
that they match exactly those of the energy model, as long as they stay
in the right ballpark, which the new ones do.

Reviewed-by: Matthias Kaehlcke <mka@...omium.org>