linux-kernel - Re: [PATCH v4 4/5] regulator: qcom: Add labibb driver

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Message-ID: <CAO_48GF9pKZCCof170TvB0ubOkecDzcGhtUUuY_Td78L1J338A@mail.gmail.com>
Date:   Wed, 17 Jun 2020 17:27:12 +0530
From:   Sumit Semwal <sumit.semwal@...aro.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     agross@...nel.org, Bjorn Andersson <bjorn.andersson@...aro.org>,
        lgirdwood@...il.com, robh+dt@...nel.org,
        Nisha Kumari <nishakumari@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, kgunda@...eaurora.org,
        Rajendra Nayak <rnayak@...eaurora.org>
Subject: Re: [PATCH v4 4/5] regulator: qcom: Add labibb driver

On Wed, 17 Jun 2020 at 17:17, Mark Brown <broonie@...nel.org> wrote:
>
> On Wed, Jun 17, 2020 at 05:12:35PM +0530, Sumit Semwal wrote:
>
> > I understand from a pure regulators' correctness point of view,
> > ENABLE_CTL should be the one checked there, so I can change the patch
> > as you suggested, but there seems to be some performance penalty
> > there.
>
> I thought the goal was to have the performance penalty to ensure that
> the regulator had actually started?
IMHO, with the poll_enabled_time mechanism added, we would not need to
wait for the full enabled_time time for the regulator to get enabled,
but we could poll (and potentially know earlier) if the regulator is
enabled.
The performance penalty I was talking, is about how should we check if
the regulator is really enabled or not - via reading the STATUS1
register, which seems to tell the status a bit faster, or via reading
the ENABLE_CTL register which we also use to enable/disable the
regulator, but which seems to be slower in updating the status.

>
> > > > The WARN_ON? This was suggested by Bjorn to catch the case where the
> > > > DT binding for a PMIC instantiates only one of the regulators.
>
> > > No, this whole loop - why this whole match and get child stuff?
>
> > This loop mechanism is what I saw in the other qcom regulators
> > upstream, so thought it was an acceptable way.
> > For the two children nodes, do you recommend another mechanism to get
> > and validate both nodes?
>
> I don't understand what you mean by "two children nodes" here?
The two 'lab' and 'ibb' regulator nodes that are part of the labibb node.

Best,
Sumit.