Re: [PATCH 3/3] arm64: dts: qcom: shikra: add vph_pwr and fix supply parent mappings

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Physically impossible hardware topology: 1.8V LDOs are configured to be supplied by a 1.396V source.
- [Medium] Missing parent supply properties for the s1 and s2 buck converters in the PM4125 regulator node.
--

--- Patch [3]: [PATCH 3/3] arm64: dts: qcom: shikra: add vph_pwr and fix supply parent mappings ---
commit 64d116ee25fe416f23ec9e23adfecfac498cc60e
Author: Rakesh Kota <rakesh.kota@oss.qualcomm.com>

arm64: dts: qcom: shikra: add vph_pwr and fix supply parent mappings

This commit adds a fixed vph_pwr regulator to represent the PM4125 charger
output. It also configures the per-group supply properties for the regulators
and adds the s1 and s4 nodes.

> diff --git a/arch/arm64/boot/dts/qcom/shikra-cqm-som.dtsi b/arch/arm64/boot/dts/qcom/shikra-cqm-som.dtsi
> index dc3861489f64d..6e4c23a730fb6 100644
> --- a/arch/arm64/boot/dts/qcom/shikra-cqm-som.dtsi
> +++ b/arch/arm64/boot/dts/qcom/shikra-cqm-som.dtsi
[ ... ]
> @@ -52,12 +62,33 @@ &pm8005_regulators {
>  &rpm_requests {
>  	regulators {
>  		compatible = "qcom,rpm-pm2250-regulators";
> +		vdd_s4-supply = <&vph_pwr>;
> +		vdd_l1-supply =  <&pm4125_s4>;

[Severity: Medium]
Are the parent supply properties for the s1 and s2 buck converters intentionally
omitted here?

Leaving out vdd_s1-supply and vdd_s2-supply prevents the regulator core from
resolving the full supply chain, which could lead to power management
dependencies failing if the parent supply is turned off while s1 or s2 are
active.

> +		vdd_l2_l3-supply =  <&pm4125_s4>;
> +		vdd_l5_l6_l7_l11_l12-supply =  <&pm4125_s4>;
> +		vdd_l8_l9-supply =  <&pm4125_s4>;
> +		vdd_l10-supply =  <&pm4125_s4>;
> +		vdd_l13_l14-supply =  <&pm4125_s1>;
> +		vdd_l15_l16-supply =  <&pm4125_s1>;

[Severity: High]
Is it possible to supply 1.8V LDOs from a 1.396V source?

The s1 regulator is configured with a 1.396V output later in this patch:

> +		pm4125_s1: s1 {
> +			regulator-min-microvolt = <1396000>;
> +			regulator-max-microvolt = <1396000>;
> +		};

But l13 through l16 are defined elsewhere in the file as requiring 1.8V:

arch/arm64/boot/dts/qcom/shikra-cqm-som.dtsi:regulators {
        pm4125_l13: l13 {
                regulator-min-microvolt = <1800000>;
                regulator-max-microvolt = <1800000>;
        };

Since a Low-Dropout Regulator (LDO) can only step down voltage, it seems like
supplying these LDOs from pm4125_s1 will prevent them from reaching their
target output voltage and cause hardware malfunction.

> +		vdd_l17_l22-supply = <&vph_pwr>;
> +		vdd_l18_l19-supply = <&vph_pwr>;
> +		vdd_l4_l20_l21-supply = <&vph_pwr>;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260717-pm2250-fix-supply-parent-v1-0-a6213a42a3b5@oss.qualcomm.com?part=3