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

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Message-ID: <qbet26mwfas4ymyy3ozl6f3a5yhgcd2e3euvrn6m3gdvnyvugh@c6yl2u2pcshz>
Date: Wed, 25 Jun 2025 04:26:29 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Varadarajan Narayanan <quic_varada@...cinc.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 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.

> 
> -Varada
> 
> > >  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