linux-kernel - Re: [PATCH v3 1/2] regulator: dt-bindings: add QCOM RPMh regulator bindings

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Message-ID: <CAD=FV=W-MLU9c-SvfLgKAKGP1eHN5xO-013f2M09XUa+QeHzrA@mail.gmail.com>
Date:   Wed, 30 May 2018 07:46:50 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     David Collins <collinsd@...eaurora.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-msm@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        devicetree@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Stephen Boyd <sboyd@...nel.org>
Subject: Re: [PATCH v3 1/2] regulator: dt-bindings: add QCOM RPMh regulator bindings

Hi,

On Wed, May 30, 2018 at 2:37 AM, Mark Brown <broonie@...nel.org> wrote:
> On Tue, May 29, 2018 at 10:30:33PM -0700, Doug Anderson wrote:
>> On Wed, May 23, 2018 at 8:56 AM, Mark Brown <broonie@...nel.org> wrote:
>
>> > Yes, that's definitely not what's expected but it's unfortunately what
>> > the firmware chose to implement so we may well be stuck with it
>> > unfortunately.
>
>> We're not really stuck with it if we do what I was suggesting.  I was
>> suggesting that every time we disable the regulator in Linux we have
>> Linux vote for the lowest voltage it's comfortable with.  Linux keeps
>> track of the true voltage that the driver wants and will always change
>> its vote back to that before enabling.  Thus (assuming Linux is OK
>> with 1.2 V - 1.4 V for a rail):
>
> That's pretty much what it should do anyway with normally designed
> hardware.

I guess the question is: do we insist that the driver include this
workaround, or are we OK with letting the hardware behave as the
hardware does?

-Doug