Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37;
MIME-Version: 1.0
References: <20231213-ad7380-mainline-v2-0-cd32150d84a3@baylibre.com>
 <20231213-ad7380-mainline-v2-3-cd32150d84a3@baylibre.com> <20231214101415.0000060c@Huawei.com>
In-Reply-To: <20231214101415.0000060c@Huawei.com>
From:   David Lechner <dlechner@baylibre.com>
Date:   Thu, 14 Dec 2023 11:33:51 +0100
Message-ID: <CAMknhBF9GtbOP_M2q8DrrMOePFOaQzGxqcS2P8OHjtGN-Z27Vg@mail.gmail.com>
Subject: Re: [PATCH v2 3/3] iio: adc: ad7380: new driver for AD7380 ADCs
To:     Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc:     linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Jonathan Cameron <jic23@kernel.org>,
        Michael Hennerich <michael.hennerich@analog.com>,
        =?UTF-8?B?TnVubyBTw6E=?= <nuno.sa@analog.com>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>, linux-kernel@vger.kernel.org,
        Stefan Popa <stefan.popa@analog.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Thu, Dec 14, 2023 at 11:14=E2=80=AFAM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
>
> On Wed, 13 Dec 2023 05:21:20 -0600
> David Lechner <dlechner@baylibre.com> wrote:
>
> > This adds a new driver for the AD7380 family ADCs.
> >
> > The driver currently implements basic support for the AD7380, AD7381,
> > AD7383, and AD7384 2-channel differential ADCs. Support for additional
> > single-ended and 4-channel chips that use the same register map as well
> > as additional features of the chip will be added in future patches.
> >
> > Co-developed-by: Stefan Popa <stefan.popa@analog.com>
> > Signed-off-by: Stefan Popa <stefan.popa@analog.com>
> > Signed-off-by: David Lechner <dlechner@baylibre.com>
>
> Just one additional comment.  I 'might' sort both this an Nuno's comment
> if Mark is fine with the SPI and no on else has review comments.
> Feel free to send a v3 though if you like ;)
>
>
> > +/* fully differential */
> > +DEFINE_AD7380_DIFFERENTIAL_2_CHANNEL(ad7380_channels, 16);
> > +DEFINE_AD7380_DIFFERENTIAL_2_CHANNEL(ad7381_channels, 14);
> > +/* pseudo differential */
> > +DEFINE_AD7380_DIFFERENTIAL_2_CHANNEL(ad7383_channels, 16);
> > +DEFINE_AD7380_DIFFERENTIAL_2_CHANNEL(ad7384_channels, 14);
> > +
> > +/* Since this is simultaneous sampling, we don't allow individual chan=
nels. */
> > +static const unsigned long ad7380_2_channel_scan_masks[] =3D {
> > +     GENMASK(2, 0), /* both ADC channels and soft timestamp */
> > +     GENMASK(1, 0), /* both ADC channels, no timestamp */
>
> https://elixir.bootlin.com/linux/v6.7-rc5/source/include/linux/iio/iio.h#=
L567
> See the comment (added recently!)

I did see this comment but this is already sorted in order of
preference, so I'm not sure why you are calling it out. Just FYI, I
guess?

>
> Also, if I remember how this works correctly there is no need to include
> the timestamp in the mask.  We do special handling for it to avoid having=
 to double
> the number of provided masks.  The details being that it uses
> iio_scan_el_ts_store rather than iio_scan_el_Store.

Indeed. I've been working ahead on adding more features and noticed
this. So we will need to find a way to say that we the timestamp
should not be allowed under certain conditions. But that will be a
discussion for a later series.

>
> So as you have it I think you'll always end up with the first entry
> and that will include a bonus bit that isn't a problem as it will match
> anyway.
>
> So just have the second entry and 0.
>
> Jonathan
>
> > +     0
> > +};