linux-kernel - Re: [PATCH v2 1/5] regulator: dt-bindings: Add Linear Technology LTM8054 regulator

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Message-ID: <CAMknhBGOpODxmzU9J9nqGDKGzn6KKFV5Ed3okLvecKtHhNRB9A@mail.gmail.com>
Date: Wed, 1 Oct 2025 13:18:51 +0200
From: David Lechner <dlechner@...libre.com>
To: Romain Gantois <romain.gantois@...tlin.com>
Cc: Conor Dooley <conor@...nel.org>, Liam Girdwood <lgirdwood@...il.com>, 
	Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jonathan Cameron <jic23@...nel.org>, Nuno Sá <nuno.sa@...log.com>, 
	Andy Shevchenko <andy@...nel.org>, Hans de Goede <hansg@...nel.org>, 
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH v2 1/5] regulator: dt-bindings: Add Linear Technology
 LTM8054 regulator

On Wed, Oct 1, 2025 at 9:12 AM Romain Gantois
<romain.gantois@...tlin.com> wrote:
>
> On Sunday, 28 September 2025 00:31:05 CEST Conor Dooley wrote:
> ...
> > > >
> > > > > +  lltc,fb-voltage-divider:
> > > > Why does this property have a ?linear? vendor prefix?
> > > > Shouldn't it be adi to match the other property and compatible?
> > >
> > > This component was originally from Linear Technology, before it was
> > > acquired by Analog Devices. The new properties and compatibles have the
> > > Analog Devices prefix, but the "fb-voltage-divider" property is already
> > > used by the LTC3676 and LTC3589 regulators, so I left the Linear
> > > Technology prefix for this one to avoid introducing a new property just
> > > to specify a vendor prefix change.
> > >
> > > I don't have a strong opinion about this though.
> >
> > Do they share the same driver?
>
> They do not. However, they use it in the exact same way, and I would've
> liked to factor out the handling of this property in a future patch. This
> would also make it easier to handle other types of feedback pin circuits
> and have a generic binding for "regulators using a feedback pin connected
> to some kind of analog circuit".
>
> For example:
>
> Vout----+
>         |
>         |
>        +++
>        | |
>        | | Rtop
>        | |
>        +++
>         |
>         |
>  FB ----+
>         |
>      +--+--+
>      |  |  |
>      |  |  |CCS
>      +--v--+
>         |
>         |
>        -+-
>         -
>
> This is all speculation at this point though, so I don't mind changing the
> property to "adi,fb-voltage-divider" and handling the different compatibles
> when it comes to it.
>

Could we just make it `fb-voltage-divider-ohms`? The -ohms suffix
makes it match the standard property-units suffix which already has
the uint32-array type. There are a couple of bindings that have
`vout-voltage-divider` without a vendor prefix, so it sounds like this
pattern is considered somewhat of a standard property already. But I
think it would be better with the -ohms suffix. For example, there is
already `gw,voltage-divider-ohms` as well. But there are so many
similar properties without the suffix, it is kind of the defacto
standard already, so might be better to stick with that rather than
making it even more different variants than there already are.