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Date: Sat, 24 Feb 2024 11:06:40 +0000
From: Jonathan Cameron <jic23@kernel.org>
To: David Lechner <dlechner@baylibre.com>
Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, Rob Herring
 <robh+dt@kernel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>,
 Michael Hennerich <michael.hennerich@analog.com>, Nuno =?UTF-8?B?U8Oh?=
 <nuno.sa@analog.com>, Liam Girdwood <lgirdwood@gmail.com>, Mark Brown
 <broonie@kernel.org>, linux-kernel@vger.kernel.org, Stefan Popa
 <stefan.popa@analog.com>, Julien Stephan <jstephan@baylibre.com>
Subject: Re: [PATCH v4 2/2] iio: adc: ad7380: new driver for AD7380 ADCs
Message-ID: <20240224110640.03f3b857@jic23-huawei>
In-Reply-To: <CAMknhBGkUP2Tdze5Fa_0qTcCP_OgcTxtczKYZiH1icfuTAEe+g@mail.gmail.com>
References: <20240110-ad7380-mainline-v4-0-93a1d96b50fa@baylibre.com>
	<20240110-ad7380-mainline-v4-2-93a1d96b50fa@baylibre.com>
	<CAMknhBGkUP2Tdze5Fa_0qTcCP_OgcTxtczKYZiH1icfuTAEe+g@mail.gmail.com>
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On Mon, 19 Feb 2024 13:47:03 -0600
David Lechner <dlechner@baylibre.com> wrote:

> On Wed, Jan 10, 2024 at 2:29=E2=80=AFPM David Lechner <dlechner@baylibre.=
com> wrote:
>=20
> ...
>=20
> > +
> > +/* fully differential */
> > +DEFINE_AD7380_DIFFERENTIAL_2_CHANNEL(ad7380_channels, 16);
> > +DEFINE_AD7380_DIFFERENTIAL_2_CHANNEL(ad7381_channels, 14);
> > +/* pseudo differential */
> > +DEFINE_AD7380_DIFFERENTIAL_2_CHANNEL(ad7383_channels, 16);
> > +DEFINE_AD7380_DIFFERENTIAL_2_CHANNEL(ad7384_channels, 14);
> > + =20
>=20
> Similar question to [1] in light of [2]: Since AD7383 and AD7384 are
> pseudo-differential, should we handle them differently? I.e. add
> aina-supply and ainb-supply DT properties for the negative inputs
> (typically a V_REF / 2 supply) and remove the differential flag from
> the channel spec.
>=20
> [1]: https://lore.kernel.org/linux-iio/CAMknhBH2Pqa9xpPxnTCxJegVTbOG-QDeJ=
A4YrQUPfj+hfSs73A@mail.gmail.com/
> [2]: https://lore.kernel.org/linux-iio/CAMknhBF5mAsN1c-194Qwa5oKmqKzef2kh=
XnqA1cSdKpWHKWp0w@mail.gmail.com/

Yes. I think that gives a more intuitive interface for users.
I don't think we need to 'fix' any drivers already upstream as
presenting these as differential is not an ABI error as far as I
am concerned. It's just less than ideal choices given our views
now! (as a result of these discussions on what pseudo differential
means in practice)

Jonathan