linux-kernel - Re: [PATCH V2 4/6] regulator: qcom_smd: Add support to define the bootup voltage

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Message-ID: <8c513ddc-435e-40ce-b1f8-84eaf8241ed4@sirena.org.uk>
Date:   Mon, 3 Apr 2023 19:14:04 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Devi Priya <quic_devipriy@...cinc.com>, agross@...nel.org,
        andersson@...nel.org, lgirdwood@...il.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        quic_srichara@...cinc.com, quic_gokulsri@...cinc.com,
        quic_sjaganat@...cinc.com, quic_kathirav@...cinc.com,
        quic_arajkuma@...cinc.com, quic_anusha@...cinc.com,
        quic_ipkumar@...cinc.com
Subject: Re: [PATCH V2 4/6] regulator: qcom_smd: Add support to define the
 bootup voltage

On Mon, Apr 03, 2023 at 07:53:48PM +0200, Konrad Dybcio wrote:
> On 3.04.2023 16:07, Devi Priya wrote:

> > But, when the regulator driver comes up, it tries to bring up the
> > regulators to the minimum supported voltage provided with the
> > regulator-min-microvolt property in the DT.

> Right, that exists.. 

> Mark, do you think it should be updated such that the requests are
> aggregated before assuming min_uV is "just fine"?

We can't tell if any consumers are ever going to appear, and the
regulator having a voltage outside of the constraints is an urgent
problem we need to fix quickly.  Since we try to bring the voltage to
the nearest end of the constraint the driver could always change the
bogus voltage it reports to one that is excessively high, this would
mean the core will try to bring the voltage down to the maximum rather
than up to the minimum.  The driver could also look at the constraints
when guessing at the hardware configuration rather than claiming an out
of spec voltage, this would mean we wouldn't need to correct anything.

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