Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230620132641.256307-1-kimseer.paller@analog.com>
 <20230620132641.256307-2-kimseer.paller@analog.com> <CAHp75VdR9W8U9VmP5WZntzB9qW3fM6qy1Q2-yeBSAG5PJimkaw@mail.gmail.com>
 <e92f919e59974bb2ae32a8d961e07538@analog.com>
In-Reply-To: <e92f919e59974bb2ae32a8d961e07538@analog.com>
From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Wed, 21 Jun 2023 11:21:17 +0300
Message-ID: <CAHp75Vf4kXi9TAvEW=JvA9SLRYuTtwwBvzH4vGoP2CRrk9vX8g@mail.gmail.com>
Subject: Re: [PATCH v7 2/2] iio: adc: max14001: New driver
To:     "Paller, Kim Seer" <KimSeer.Paller@analog.com>
Cc:     "jic23@kernel.org" <jic23@kernel.org>,
        "lars@metafoo.de" <lars@metafoo.de>,
        "lgirdwood@gmail.com" <lgirdwood@gmail.com>,
        "broonie@kernel.org" <broonie@kernel.org>,
        "Hennerich, Michael" <Michael.Hennerich@analog.com>,
        "robh@kernel.org" <robh@kernel.org>,
        "krzysztof.kozlowski@linaro.org" <krzysztof.kozlowski@linaro.org>,
        "conor+dt@kernel.org" <conor+dt@kernel.org>,
        "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Wed, Jun 21, 2023 at 3:38=E2=80=AFAM Paller, Kim Seer
<KimSeer.Paller@analog.com> wrote:
> > From: Andy Shevchenko <andy.shevchenko@gmail.com>
> > Sent: Tuesday, June 20, 2023 11:15 PM
> > On Tue, Jun 20, 2023 at 4:27=E2=80=AFPM Kim Seer Paller
> > <kimseer.paller@analog.com> wrote:

...

> > > +       /*
> > > +        * Align received data from the receive buffer, reversing and=
 reordering
> > > +        * it to match the expected MSB-first format.
> > > +        */
> > > +       *data =3D (__force u16)(be16_to_cpu(bitrev16(st->spi_rx_buffe=
r))) &
> > > +                                                       MAX14001_DATA=
_MASK;
> >
> > Using __force in the C files is somehow stinky.

...

> > > +       /*
> > > +        * Convert transmit buffer to big-endian format and reverse t=
ransmit
> > > +        * buffer to align with the LSB-first input on SDI port.
> > > +        */
> > > +       st->spi_tx_buffer =3D (__force u16)(cpu_to_be16(bitrev16(
> >
> > You have a different type of spi_tx_buffer than u16, don't you?
>
> I have the same type of spi_tx_buffer as u16.

And you should have __be16.

> Other than using force cast, is there any way to resolve the endian warni=
ng? I have
> actually swapped the order of bitrev16() and cpu_to_be16/be16_to_cpu() fu=
nctions.
> I have tested and they also work fine.

You really have to get it correct on both LE and BE architectures.

--=20
With Best Regards,
Andy Shevchenko