linux-kernel - Re: [PATCH v4 4/5] iio: adc: ti-adc128s052: Add lower resolution devices support

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Message-ID: <aGHiPpLeIB6pLb9I@dev-linux>
Date: Sun, 29 Jun 2025 18:02:54 -0700
From: Sukrut Bellary <sbellary@...libre.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: David Lechner <dlechner@...libre.com>,
	Jonathan Cameron <jic23@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Matti Vaittinen <mazziesaccount@...il.com>,
	Nuno Sá <nuno.sa@...log.com>,
	Andy Shevchenko <andy@...nel.org>,
	Angelo Compagnucci <angelo.compagnucci@...il.com>,
	Nishanth Menon <nm@...com>, linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 4/5] iio: adc: ti-adc128s052: Add lower resolution
 devices support

On Sun, Jun 29, 2025 at 09:06:47AM +0300, Andy Shevchenko wrote:
> On Sun, Jun 29, 2025 at 2:30 AM David Lechner <dlechner@...libre.com> wrote:
> >
> > On 6/28/25 6:09 PM, Sukrut Bellary wrote:
> > > On Sat, Jun 14, 2025 at 09:45:43PM +0300, Andy Shevchenko wrote:
> > >> On Sat, Jun 14, 2025 at 12:15 PM Sukrut Bellary <sbellary@...libre.com> wrote:
> > >>>
> > >>> The adcxx communicates with a host processor via an SPI/Microwire Bus
> > >>> interface. The device family responds with 12-bit data, of which the LSB bits
> > >>> are transmitted by the lower resolution devices as 0.
> > >>> The unavailable bits are 0 in LSB.
> > >>> Shift is calculated per resolution and used in scaling and raw data read.
> > >>>
> > >>> Lets reuse the driver to support the family of devices with name
> > >>> ADC<bb><c>S<sss>, where
> > >>
> > >> I believe it's incorrect, i.e. it's something like ...S<ss><?>, where
> > >> <?> is something you need to clarify, and <ss> is definitely a speed
> > >> in kSPS.
> > >>
> > > Thank you for the review.
> > > I am not sure about the last s in <sss>.
> > > It could be TI's silicon spins versioning.
> > > I couldn't find any information about it in any of the datasheets.
> > > I can drop the last s or mark it as <ssx> and specify the first two <ss> as
> > > maximum speed.
> > >
> > I have a hunch that the last digit has to do with pinout/number of
> > power supplies. adc128s052 has two supplies V_A and V_D while the
> > others only have V_A.
> >
> > If this sounds vaguely familiar, it is because it was discussed
> > today in this thread [1] that Jonathan CC'ed you in. :-)
> 
> With all this being said, please, switch to <ss><p> and describe <p>,
> but with the caveat that the <p> is empirically deducted based on what
> community observes.
> 
> > [1]: https://lore.kernel.org/linux-iio/20250628162910.1256b220@jic23-huawei/
> 
Ok, sure. I will use this in v5.

> -- 
> With Best Regards,
> Andy Shevchenko