linux-kernel - Re: [PATCH] arm64: dts: qcom: ipq9574: Fix 'l2' regulator min/max voltages

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Message-ID: <aFvQ96h+BdRf5ma3@hu-varada-blr.qualcomm.com>
Date: Wed, 25 Jun 2025 16:05:35 +0530
From: Varadarajan Narayanan <quic_varada@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
CC: Konrad Dybcio <konrad.dybcio@....qualcomm.com>, <andersson@...nel.org>,
        <konradybcio@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
        <conor+dt@...nel.org>, <lumag@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: dts: qcom: ipq9574: Fix 'l2' regulator min/max
 voltages

On Wed, Jun 25, 2025 at 04:26:29AM +0300, Dmitry Baryshkov wrote:
> On Tue, Jun 24, 2025 at 11:38:34AM +0530, Varadarajan Narayanan wrote:
> > On Mon, Jun 23, 2025 at 01:34:22PM +0200, Konrad Dybcio wrote:
> > > On 6/23/25 1:32 PM, Varadarajan Narayanan wrote:
> > > > The min and max voltages on l2 regulator is 850000uV. This was
> > > > incorrectly set at 1800000uV earlier and that affected the
> > > > stability of the networking subsystem.
> > > >
> > > > Fixes: d5506524d9d9 ("arm64: dts: qcom: ipq9574: Add LDO regulator node")
> > > > Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
> > > > ---
> > >
> > > Shouldn't there be a consumer for it, instead of it being always-on?
> >
> > The uniphy block is the consumer of this voltage. The PMIC configures it
> > to 850000uV based on OTP settings and s/w doesn't change it as uniphy
> > doesn't do scaling.
>
> Please express this in DT terms, specifying the regulator as a supplier
> to the uniphy and then making the uniphy driver use that supply.

Sure, we will update UNIPHY patch series [1] to enable this voltage supplier.

Thanks
Varada

1 - https://lore.kernel.org/linux-arm-msm/20250207-ipq_pcs_6-14_rc1-v5-0-be2ebec32921@quicinc.com/

> > > >  arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi b/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
> > > > index bdb396afb992..21b04a2c629d 100644
> > > > --- a/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
> > > > +++ b/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
> > > > @@ -106,8 +106,8 @@ ipq9574_s1: s1 {
> > > >  		};
> > > >
> > > >  		mp5496_l2: l2 {
> > > > -			regulator-min-microvolt = <1800000>;
> > > > -			regulator-max-microvolt = <1800000>;
> > > > +			regulator-min-microvolt = <850000>;
> > > > +			regulator-max-microvolt = <850000>;
> > > >  			regulator-always-on;
> > > >  			regulator-boot-on;
> > > >  		};
> > > >
> > > > base-commit: 5d4809e25903ab8e74034c1f23c787fd26d52934
>
> --
> With best wishes
> Dmitry