linux-kernel - Re: [PATCH v2] arm64: dts: qcom: sm8550: Correct the min/max voltages for vreg_l6n

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Message-ID: <CADhhZXYZGO7Ns6R4JEyrt43+HGBuVwKz8hRiA7cxeTfg6egVcg@mail.gmail.com>
Date: Thu, 26 Jun 2025 17:09:45 +0530
From: Kamal Wadhwa <kamal.wadhwa@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH v2] arm64: dts: qcom: sm8550: Correct the min/max voltages
 for vreg_l6n_3p3

Hi Konrad,

On Mon, Jun 23, 2025 at 4:53 PM Konrad Dybcio
<konrad.dybcio@....qualcomm.com> wrote:
>
> On 6/20/25 5:29 PM, Kamal Wadhwa wrote:
> > Voltage regulator 'vreg_l6n_3p3' max-microvolt prop is currently
> > configured at 3304000uV in different sm8550 board files. However this
> > is not a valid voltage value for 'pmic5_pldo502ln' type voltage
> > regulators.
> >
> > Check below the max value(3200mV) in the regulator summary for min/max
> > used as 2800mV/3304mV in DT:-
> >
> > logs:
> >
> > [    0.294781] vreg_l6n_3p3: Setting 2800000-3304000uV
> >
> > regulator summary:
> >
> > regulator     use open bypass  opmode   voltage current  min     max
> > ---------------------------------------------------------------------
> > ..
> > vreg_l6n_3p3   0    0    0     normal   2800mV   0mA  2800mV  3200mV
> > ..
> >
> > Correct the min/max value to 3200000uV, as that is the closest valid
> > value to 3.3V and Hardware team has also confirmed that its good to
> > support the consumers(camera sensors) of this regulator.
> >
> > Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>
> > Signed-off-by: Kamal Wadhwa <kamal.wadhwa@....qualcomm.com>
> > ---
>
> FWIW it seems like 3.312v (which is slightly above the previous
> value) is also supported:
>
> static const struct rpmh_vreg_hw_data pmic5_pldo502ln = {
>         .regulator_type = VRM,
>         .ops = &rpmh_regulator_vrm_ops,
>         .voltage_ranges = (struct linear_range[]) {
>                 REGULATOR_LINEAR_RANGE(1800000, 0,  2,  200000),
>                 REGULATOR_LINEAR_RANGE(2608000, 3,  28, 16000),
>                 REGULATOR_LINEAR_RANGE(3104000, 29, 30, 96000),
>                 REGULATOR_LINEAR_RANGE(3312000, 31, 31, 0),
>         },
>         .n_linear_ranges = 4,
>         .n_voltages = 32,
>         .pmic_mode_map = pmic_mode_map_pmic5_ldo_hpm,
>         .of_map_mode = rpmh_regulator_pmic4_ldo_of_map_mode,
> };

Yes, originally I was planning to share the change for 3304mV -> 3312mV.
However, while testing, I realized that I would also need changes in
firmware( to allow for a 3312mV max limit). so during internal discussion
it was clarified that all the consumers on L6N can work fine with 3.2v.


>
> but if the hw folks say we can do with the lower value, it's probably
> even better

Yes. Thanks for affirming.

Thanks,
Kamal

>
> Konrad