linux-kernel - Re: [PATCH v3 3/6] dt-bindings: mfd: da9062: add regulator voltage selection documentation

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Message-ID: <20200107130911.GD4877@sirena.org.uk>
Date:   Tue, 7 Jan 2020 13:09:11 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Marco Felsch <m.felsch@...gutronix.de>
Cc:     "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Support Opensource <Support.Opensource@...semi.com>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        "bgolaszewski@...libre.com" <bgolaszewski@...libre.com>,
        "andrew@...id.au" <andrew@...id.au>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "joel@....id.au" <joel@....id.au>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 3/6] dt-bindings: mfd: da9062: add regulator voltage
 selection documentation

On Tue, Jan 07, 2020 at 09:36:54AM +0100, Marco Felsch wrote:
> On 19-12-17 12:58, Mark Brown wrote:

> > This doesn't say anything about how the GPIO input is expected to be
> > controlled, for voltage setting any runtime control would need to be
> > done by the driver and it sounds like that's all that can be controlled.
> > The way this reads I'd expect one use of this to be for fast voltage
> > setting for example (you could even combine that with suspend sequencing
> > using the internal sequencer if you mux back to the sequencer during
> > suspend).

> The input signal is routed trough the da9062 gpio block to the
> regualtors. You can't set any voltage value using a gpio instead you
> decide which voltage setting is applied. The voltage values for
> runtime/suspend comes from the dt-data. No it's not just a fast
> switching option imagine the system suspend case where the cpu and soc
> voltage can be reduced to a very low value. Older soc's like the imx6
> signaling this state by a hard wired gpio line because the soc and
> cpu cores don't work properly on such low voltage values. This is
> my use case and I can't use the sequencer.

My point is that I can't tell any of this from the description.

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