linux-kernel - Re: [PATCH v6 0/5] AD7949 Fixes

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Message-ID: <CAHp75VdOMg-7xX+KbdaDt5tduPhorujFwvpMPmdHKMVg=vj2Ew@mail.gmail.com>
Date:   Mon, 16 Aug 2021 11:08:19 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Liam Beguin <liambeguin@...il.com>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Charles-Antoine Couret <charles-antoine.couret@...ensium.com>,
        Nuno Sá <Nuno.Sa@...log.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v6 0/5] AD7949 Fixes

On Mon, Aug 16, 2021 at 12:35 AM Liam Beguin <liambeguin@...il.com> wrote:
>
> While working on another series[1] I ran into issues where my SPI
> controller would fail to handle 14-bit and 16-bit SPI messages. This
> addresses that issue and adds support for selecting a different voltage
> reference source from the devicetree.
>
> v1 was base on a series[2] that seems to not have made it all the way,
> and was tested on an ad7689.
>
> v6 drops support for per channel vref selection.
> After switching the voltage reference, readings take a little while to
> stabilize, invalidating consecutive readings.
>
> This could've been addressed by adding more dummy cycles at the expense
> of speed, but discussing the issue with colleagues more involved in
> hardware design, it turns out these circuits are usually designed with a
> single vref in mind.
>
> [1] https://patchwork.kernel.org/project/linux-iio/list/?series=511545
> [2] https://patchwork.kernel.org/project/linux-iio/list/?series=116971&state=%2A&archive=both
>
> Changes since v5:
> - rename defines: s/AD7949_CFG_BIT_/AD7949_CFG_MASK_/g
> - rename AD7949_MASK_TOTAL to match other defines

> - make vref selection global instead of per channel, and update
>   dt-bindings

Same as per v5: is it a hardware limitation?
It's unclear to me what happened here.

> - reword commits 2/5, 3/5, and 4/5
> - move bits_per_word configuration to struct spi_device, and switch to
>   spi_{read,write}.

-- 
With Best Regards,
Andy Shevchenko