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

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Message-ID: <CAHp75VeXxPum242gE8NoC9f8ZKkFg2FTAkmBXvY9m-BNz6+i7g@mail.gmail.com>
Date: Sun, 29 Jun 2025 09:06:47 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: David Lechner <dlechner@...libre.com>
Cc: Sukrut Bellary <sbellary@...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 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/

-- 
With Best Regards,
Andy Shevchenko