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Date: Thu, 10 Sep 2026 03:43:05 +0100
From: Jonathan Cameron <jic23@kernel.org>
To: "Kurt Borja" <kuurtb@gmail.com>
Cc: "David Lechner" <dlechner@baylibre.com>, "Rob Herring"
 <robh@kernel.org>, "Krzysztof Kozlowski" <krzk+dt@kernel.org>, "Conor
 Dooley" <conor+dt@kernel.org>, Nuno =?UTF-8?B?U8Oh?= <nuno.sa@analog.com>,
 "Andy Shevchenko" <andy@kernel.org>, <linux-iio@vger.kernel.org>,
 <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 03/10] iio: adc: add the ti-ads1262 driver
Message-ID: <20260910034305.7ac409ca@jic23-hlaptop>
In-Reply-To: <DL8IE3OUIUZ4.2SND39L7P03VL@gmail.com>
References: <20260828-ads126x-v4-0-1dc27e9c0260@gmail.com>
	<20260828-ads126x-v4-3-1dc27e9c0260@gmail.com>
	<bc00d888-9944-4a22-88e3-8f4d7384d037@baylibre.com>
	<DL8IE3OUIUZ4.2SND39L7P03VL@gmail.com>
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...

> >> +static int ads1262_fwnode_xlate(struct iio_dev *indio_dev,
> >> +				const struct fwnode_reference_args *iiospec)
> >> +{
> >> +	/* REVISIT: the auxiliary ADC (ADC2) is currently not supported */
> >> +	if (iiospec->nargs > 1 && iiospec->args[1])
> >> +		return -EINVAL;
> >> +
> >> +	if (!iiospec->nargs)
> >> +		return 0;
> >> +
> >> +	for (unsigned int i = 0; i < indio_dev->num_channels; i++) {  
> >
> > Won't this include the timestamp channel?  
> 
> Yes, I'll fix it.
> 
> >  
> >> +		if (indio_dev->channels[i].address == iiospec->args[0])  
> >
> > I don't think .address is the right thing to use here (it is coming from
> > reg in the devcietree). I would expect channel. Otherwise consumers in the
> > devicetree have to be away of how channels were assigned rather than picking
> > the datasheet channel number.  
> 
> I was very confused about what approach should I take here. All channels
> in this chip are actually differential. In that case should I make
> #io-channel-cells = 3 i.e. positive, negative and ADC?

Yes. Given the flexibility that makes sense.
You would need to sanity check the channel is actually present that
matches those choices though.

> 
> >
> > And the devicetree bindings should mention the monitor channel numbers (11 - 14).
> >  
> >> +			return i;
> >> +	}
> >> +
> >> +	return -EINVAL;
> >> +}
> >> +  
> >
> > ...