linux-kernel - Re: [PATCH 5/5] iio: adc: ad7606: add gain calibration support

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Message-ID: <CAHp75VfBrodRH0gW8teULNSt3f_uJA0Ze+P+YOTKLhtec84-3Q@mail.gmail.com>
Date: Wed, 30 Apr 2025 01:34:41 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Angelo Dureghello <adureghello@...libre.com>
Cc: Jonathan Cameron <jic23@...nel.org>, David Lechner <dlechner@...libre.com>, 
	Nuno Sá <nuno.sa@...log.com>, 
	Andy Shevchenko <andy@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>, 
	Michael Hennerich <Michael.Hennerich@...log.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, linux-iio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 5/5] iio: adc: ad7606: add gain calibration support

On Tue, Apr 29, 2025 at 4:08 PM Angelo Dureghello
<adureghello@...libre.com> wrote:
>
> From: Angelo Dureghello <adureghello@...libre.com>
>
> Add gain calibration support, using resistor values set on devicetree,
> values to be set accordingly with ADC external RFilter, as explained in
> the ad7606c-16 datasheet, rev0, page 37.
>
> Usage example in the fdt yaml documentation.

...

> +#define AD7606_CALIB_GAIN_MIN  0
> +#define AD7606_CALIB_GAIN_STEP 1024
> +#define AD7606_CALIB_GAIN_MAX  65536

Are those values in decimal in the datasheet?
It looks to me something like

_MAX = (64 * _STEP)

but is it for real? Usually values are limited by the amount of bits
in the HW, here it spans over 65 steps, i.e. 7 bits would be needed...
Confusing.

-- 
With Best Regards,
Andy Shevchenko