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From: Ulf Hansson <ulf.hansson@linaro.org>
Date: Wed, 3 Apr 2024 13:20:58 +0200
Message-ID: <CAPDyKFous+aoopf+=ZRugR78jyekobODqn7tqWRCyirPD+=eYw@mail.gmail.com>
Subject: Re: [PATCH 5/5] arm64: dts: qcom: x1e80100: Enable cpufreq
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: Sibi Sankar <quic_sibis@quicinc.com>, cristian.marussi@arm.com, andersson@kernel.org, 
	konrad.dybcio@linaro.org, jassisinghbrar@gmail.com, robh+dt@kernel.org, 
	krzysztof.kozlowski+dt@linaro.org, linux-kernel@vger.kernel.org, 
	linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, 
	quic_rgottimu@quicinc.com, quic_kshivnan@quicinc.com, conor+dt@kernel.org, 
	quic_gkohli@quicinc.com, quic_nkela@quicinc.com, quic_psodagud@quicinc.com
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On Tue, 2 Apr 2024 at 13:10, Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Thu, Mar 28, 2024 at 03:20:44PM +0530, Sibi Sankar wrote:
> > Enable cpufreq on X1E80100 SoCs through the SCMI perf protocol node.
> >
> > Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
> > ---
> >  arch/arm64/boot/dts/qcom/x1e80100.dtsi | 27 ++++++++++++++++++++++++++
> >  1 file changed, 27 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/qcom/x1e80100.dtsi b/arch/arm64/boot/dts/qcom/x1e80100.dtsi
> > index 4e0ec859ed61..d1d232cd1f25 100644
> > --- a/arch/arm64/boot/dts/qcom/x1e80100.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/x1e80100.dtsi
> > @@ -68,6 +68,7 @@ CPU0: cpu@0 {
> >                       compatible = "qcom,oryon";
> >                       reg = <0x0 0x0>;
> >                       enable-method = "psci";
> > +                     clocks = <&scmi_dvfs 0>;
> >                       next-level-cache = <&L2_0>;
> >                       power-domains = <&CPU_PD0>;
> >                       power-domain-names = "psci";
>
>
> Any reason why you wouldn't want to use the new genpd based perf controls.
> IIRC it was added based on mainly Qcom platform requirements.
>
> -                     clocks = <&scmi_dvfs 0>;
>                       next-level-cache = <&L2_0>;
> -                     power-domains = <&CPU_PD0>;
> -                     power-domain-names = "psci";
> +                     power-domains = <&CPU_PD0>, <&scmi_dvfs 0>;
> +                     power-domain-names = "psci", "perf";
>
>
> And the associated changes in the scmi dvfs node for cells property.
>
> This change is OK but just wanted to check the reasoning for the choice.

To me, it seems reasonable to move to the new binding with
#power-domain-cells for protocol@13. This becomes more future proof,
as it can then easily be extended to be used beyond CPUs.

That said, I just submitted a patch [1] to update the examples in the
scmi DT doc to use  #power-domain-cells in favor of #clock-cells. I
don't know if there is a better way to promote the new bindings?
Perhaps moving Juno to use this too?

Kind regards
Uffe

[1]
https://lore.kernel.org/all/20240403111106.1110940-1-ulf.hansson@linaro.org/