linux-kernel - Re: [PATCH v2 2/2] iio: potentiometer: Add driver support for AD5110

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Message-ID: <013bcb79-c496-44d8-2e93-57eb57834ee0@metafoo.de>
Date:   Wed, 11 Aug 2021 10:15:09 +0200
From:   Lars-Peter Clausen <lars@...afoo.de>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Mugilraj Dhavachelvan <dmugil2000@...il.com>
Cc:     "Bogdan, Dragos" <Dragos.Bogdan@...log.com>,
        Darius <Darius.Berghe@...log.com>,
        Rob Herring <robh+dt@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Chris Packham <chris.packham@...iedtelesis.co.nz>,
        Slawomir Stepien <sst@...zta.fm>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org
Subject: Re: [PATCH v2 2/2] iio: potentiometer: Add driver support for AD5110

On 8/10/21 2:49 PM, Andy Shevchenko wrote:
>
>> +       data->tol = data->cfg->kohms * (val & GENMASK(6, 0)) * 10 / 8;
>> +       if (!(val & BIT(7)))
>> +               data->tol *= -1;
> Shouldn't you simple use corresponding sign_extend*()?
The data is encoded a sign-magnitude. sign_extend() works for two's 
complement numbers.