linux-kernel - Re: [PATCH 1/4] devicetree: add a binding for a regulator that constrains its supply

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Date:	Mon, 24 Nov 2014 18:04:22 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Alban Bedel <alban.bedel@...onic-design.de>
Cc:	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Grant Likely <grant.likely@...aro.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Kumar Gala <galak@...eaurora.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Mark Rutland <mark.rutland@....com>,
	Pawel Moll <pawel.moll@....com>,
	Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 1/4] devicetree: add a binding for a regulator that
 constrains its supply

On Mon, Nov 24, 2014 at 06:12:33PM +0100, Alban Bedel wrote:

> Using this driver the DTS for the add-on board can further constrain
> this supply to get the voltage it need, for example 3.3V. I understand

> I saw 3 ways to solve this problem:

> 1) This, use a "filter" regulator
> 2) Extend each and every driver that use a voltage regulator to
>    optionally set the voltage
> 3) Include the required range in the phandle reference

> #1 was the easiest :) #2 doesn't seems practical to me, #3 seems pretty
> good but I'm really not sure if that would be acceptable.

The DT overlay for the add on board should be setting the constraints
for the parent regulator.  I wouldn't expect the final DT to look any
different to how it looks with no hardware modularity unless the actual
module is interesting enough to have a driver of its own.

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