linux-kernel - RE: [PATCH 0/2] add AD8460 DAC driver

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Message-ID: 
 <DM8PR03MB62132D6B31F23A7E8406EC4591D92@DM8PR03MB6213.namprd03.prod.outlook.com>
Date: Sun, 7 Jul 2024 23:29:43 +0000
From: "Tinaco, Mariel" <Mariel.Tinaco@...log.com>
To: Jonathan Cameron <jic23@...nel.org>
CC: David Lechner <dlechner@...libre.com>,
        "linux-iio@...r.kernel.org"
	<linux-iio@...r.kernel.org>,
        "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>,
        Lars-Peter Clausen <lars@...afoo.de>, Rob
 Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor
 Dooley <conor+dt@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>, Mark Brown
	<broonie@...nel.org>,
        "Hennerich, Michael" <Michael.Hennerich@...log.com>,
        Marcelo Schmitt <marcelo.schmitt1@...il.com>,
        Dimitri Fedrau
	<dima.fedrau@...il.com>,
        Guenter Roeck <linux@...ck-us.net>
Subject: RE: [PATCH 0/2] add AD8460 DAC driver



> -----Original Message-----
> From: Jonathan Cameron <jic23@...nel.org>
> Sent: Saturday, June 29, 2024 2:40 AM
> To: Tinaco, Mariel <Mariel.Tinaco@...log.com>
> Cc: David Lechner <dlechner@...libre.com>; linux-iio@...r.kernel.org;
> devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; Lars-Peter Clausen
> <lars@...afoo.de>; Rob Herring <robh@...nel.org>; Krzysztof Kozlowski
> <krzk+dt@...nel.org>; Conor Dooley <conor+dt@...nel.org>; Liam Girdwood
> <lgirdwood@...il.com>; Mark Brown <broonie@...nel.org>; Hennerich,
> Michael <Michael.Hennerich@...log.com>; Marcelo Schmitt
> <marcelo.schmitt1@...il.com>; Dimitri Fedrau <dima.fedrau@...il.com>;
> Guenter Roeck <linux@...ck-us.net>
> Subject: Re: [PATCH 0/2] add AD8460 DAC driver
> 
> [External]
> 
> 
> > >
> > > > >   * Programmable quiescent current (optional)
> > > Could probably figure out a suitable control for this, but I'm not
> > > entirely sure what it is :)
> >
> > Thinking about it, wouldn't the raw attribute be a suitable control
> > for this? This Value is relative to nominal supply current and acts as a
> "monotonic but nonlinear"
> > multiplier.
> > A register value maps to a current level from 0 to 2 times the nominal
> > current supplied. I also thought that it could be hardware gain but
> > the gain computation wasn't explicitly indicated in the datasheet and
> > there is not yet "current_hardwaregain" attribute available in the ABI. So I
> settled with raw.
> 
> I don't entirely understand what is actually for, but a raw current output might
> be appropriate.
> 
> >I
> > Think there would only be an issue of we expose the "processed"
> >attribute  Because it has a particular computation. But I'm not
> >planning to expose the  Processed attribute
> 
> Is there any reason someone might in future though?

They would have to measure the supply current to see the effect of
This attribute, then that would be the "processed" value. I don't think
that would be necessary

> 
> >
> > > > >   * Thermal monitoring is done by measuring voltage on TMP pin
> > > > > (unlikely to be included)
> > >
> > > If you did want to, the usual trick for these is to include an
> > > optional use as a consumer of an IIO provider which would be a separate
> ADC.
> >
> > I included this in my current revision, thanks for the idea. Although
> > the optional use Isn’t yet available in the consumer API. My question
> > is, in case the ADC channel to read The TMP pin is not available,
> > should I still make the temp raw value available and Set to 0? Or
> > should the temp raw attribute be unavailable or unlisted completely from IIO
> Info.
> If no ADC channel then remove it from the chan_spec.  That probably means you
> need separate arrays of struct iio_chan_spec for the two case.
> 
> Jonathan
> 
> > > > >
> > > >
> > > > Adding myself to the cc: here since I'm interested to see what
> > > > Jonathan (or anyone else) has to say about the fault monitoring.
> > >
> > > Jonathan