linux-kernel - Re: [PATCH v3 1/2] dt-bindings: regulator: qcom,rpmh: Allow regulator-off-on-delay-us

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Message-ID: <20260206161952.ctmzghln5tkqzvn6@hu-kamalw-hyd.qualcomm.com>
Date: Fri, 6 Feb 2026 21:49:52 +0530
From: Kamal Wadhwa <kamal.wadhwa@....qualcomm.com>
To: Mark Brown <broonie@...nel.org>
Cc: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Rob Herring <robh@...nel.org>,
        Jishnu Prakash <jishnu.prakash@....qualcomm.com>,
        Saikiran <bjsaikiran@...il.com>, lgirdwood@...il.com,
        andersson@...nel.org, konradybcio@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        krzk+dt@...nel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v3 1/2] dt-bindings: regulator: qcom,rpmh: Allow
 regulator-off-on-delay-us

On Tue, Feb 03, 2026 at 04:30:27PM +0000, Mark Brown wrote:
> On Tue, Feb 03, 2026 at 09:50:05PM +0530, Kamal Wadhwa wrote:
> 
> > But I'm wondering if this is really a 'slow discharge' issue, because if the
> > caps discharge slowly.. shouldn't the rails be turning back ON faster
> > compared to when they are completely discharged (fast discharge case without
> > bulk caps)?
> 
> The issue is that some of the supplies fall to a level where they cause
> disruption to the devices using them but not far enough to put them back
> into a power on reset state, the device browns out somehow (I'm guessing
> some retained state is corrupted).  Ideally they'd have POR circuits
> that handle this case well but apparently that's not the case.

I have checked:
- ALL the pm8010 regulators have the PD enabled in OFF state by default.
- From kernel enable/disable of regulator PD settings is not allowed. Its set
  from the boot and stays as-is later.

But since its already enabled with strong PD, i guess it would not be needed
anyway.

Regards,
Kamal