linux-kernel - Re: [PATCH] regulator: twl: mark vdd1/2 as continuous on twl4030

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Message-ID: <20190617170255.GF5316@sirena.org.uk>
Date:   Mon, 17 Jun 2019 18:02:55 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Andreas Kemnade <andreas@...nade.info>
Cc:     tony@...mide.com, lgirdwood@...il.com, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        sboyd@...nel.org, nm@...com, vireshk@...nel.org,
        letux-kernel@...nphoenux.org
Subject: Re: [PATCH] regulator: twl: mark vdd1/2 as continuous on twl4030

On Mon, Jun 17, 2019 at 06:27:43PM +0200, Andreas Kemnade wrote:

> Citing tps65950 trm page 55:

> The device contains three switch-mode power supplies (SMPS):
> • VDD1: 1.2-A, buck DC/DC converter (VOUT = 0.6 V to 1.45 V, in steps of 12.5 mV)
> • VDD2: 600-mA buck DC/DC converter (VOUT = 0.6 V to 1.45 V, in steps of 12.5 mV, and 1.5 V as a
>    single programmable value)

> you are right, they are not really continuous. So should I add these
> 68 steps they have as a voltage list?

There's helpers for linear mappings, you should be able to use those
(see helpers.c).

> I think they are nearly continuous, so we should IMHO rather take that
> not that strict. I guess there are no really continuous regulators, all
> have steps as voltage is specified in a limited resolution. So what is
> the exact meaning of that flag here?

This was added for devices with extremely high resolution interfaces
like some microcontroller interfaces that take voltage values directly
(mirroring the regulator API) or PWM regulators - it's for cases where
enumerating all the voltages is unreasonable.  The TWL4030 regulators
look fairly standard in comparison.

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