linux-kernel - Re: [RFC 4/8] regulator: core: Check enabling bypass respects constraints

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Message-ID: <20170407112212.gzv3p7ldkh62657m@sirena.org.uk>
Date:   Fri, 7 Apr 2017 12:22:12 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Leonard Crestez <leonard.crestez@....com>
Cc:     Sascha Hauer <kernel@...gutronix.de>,
        Liam Girdwood <lgirdwood@...il.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Shawn Guo <shawnguo@...nel.org>,
        Robin Gong <yibin.gong@....com>,
        Anson Huang <Anson.Huang@....com>,
        Irina Tirdea <irina.tirdea@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Fabio Estevam <fabio.estevam@....com>,
        Octavian Purdila <octavian.purdila@....com>,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC 4/8] regulator: core: Check enabling bypass respects
 constraints

On Fri, Apr 07, 2017 at 01:51:52PM +0300, Leonard Crestez wrote:

> It currently seems to work how I expect but from your statement it's
> not clear if it's entirely intentional.

The current behaviour of bypassed regulators is intentional.

> > > Or should a bypassed regulator ignore all other requests? One of the
> > > behaviors that this patch series relies on is that calling set_voltage
> > > on a bypassed regulator propagates this request to the supply and picks
> > > the minimum voltage there. An alternative implementation would be to

> > Yes, the expectation is that if anything is being changed it won't have
> > any effect until regulation is reenabled but we're not particularly
> > expecting much activity on bypassed regulators.

> OK, so it is up to consumers to ensure the supply voltage is acceptable
> before allowing bypass. If they want to do something clever they should
> register as a consumer to the supply as well.

No, that's not expected either - one or the other is fine but both isn't
expected.  What you're looking for here is something logically different
to bypass even if the hardware implementation ends up the same.

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