linux-kernel - Re: [PATCH v3 1/4] arm64: dts: qcom: sc7180: Don't enable lpass clocks by default

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Date:   Thu, 16 Mar 2023 00:28:45 +0000
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Nikita Travkin <nikita@...n.ru>
Cc:     agross@...nel.org, andersson@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, konrad.dybcio@...aro.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v3 1/4] arm64: dts: qcom: sc7180: Don't enable lpass
 clocks by default

On Wed, Mar 15, 2023 at 08:43:08PM +0500, Nikita Travkin wrote:
> lpass clocks are usually blocked from HLOS by the firmware and
> instead are managed by the ADSP. Mark them as reserved and explicitly
> enable in the CrOS boards that have special, cooperative firmware.
> 
> Signed-off-by: Nikita Travkin <nikita@...n.ru>
> ---
>  arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 8 ++++++++
>  arch/arm64/boot/dts/qcom/sc7180.dtsi         | 4 ++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> index 423630c4d02c..26def6e12723 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> @@ -785,6 +785,14 @@ alc5682: codec@1a {
>  	};
>  };
>  
> +&lpasscc {
> +	status = "okay";
> +};
> +
> +&lpass_hm {
> +	status = "okay";
> +};
> +
>  &lpass_cpu {
>  	status = "okay";
>  
> diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> index 53f0076f20f6..f0de177981f9 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> @@ -3623,6 +3623,8 @@ lpasscc: clock-controller@...00000 {
>  			power-domains = <&lpass_hm LPASS_CORE_HM_GDSCR>;
>  			#clock-cells = <1>;
>  			#power-domain-cells = <1>;
> +
> +			status = "reserved"; /* Controlled by ADSP */

Why not "disabled"? I see "reserved" is used in a couple of other
instances, but it doesn't appear in Documentation/devicetree/bindings/,
so it doesn't seem to have a well defined meaning that distinguishes it
from "disabled".

>  		};
>  
>  		lpass_cpu: lpass@...87000 {
> @@ -3671,6 +3673,8 @@ lpass_hm: clock-controller@...00000 {
>  
>  			#clock-cells = <1>;
>  			#power-domain-cells = <1>;
> +
> +			status = "reserved"; /* Controlled by ADSP */
>  		};
>  	};
>  
> -- 
> 2.39.2
>