linux-kernel - Re: [PATCH v2] iio: adc: ad7944: simplify adi,spi-mode property parsing

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Date: Tue, 19 Mar 2024 10:28:31 -0500
From: David Lechner <dlechner@...libre.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Jonathan Cameron <jic23@...nel.org>, Michael Hennerich <michael.hennerich@...log.com>, 
	Nuno Sá <nuno.sa@...log.com>, linux-iio@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: adc: ad7944: simplify adi,spi-mode property parsing

On Tue, Mar 19, 2024 at 10:01 AM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Tue, Mar 19, 2024 at 4:28 PM David Lechner <dlechner@...libre.com> wrote:
> >
> > This simplifies the adi,spi-mode property parsing by using
> > device_property_match_property_string() instead of two separate
> > functions. Also, the error return value is now more informative
> > in cases where there was problem parsing the property.
>
> a problem
>
> ...
>
> > +       ret = device_property_match_property_string(dev, "adi,spi-mode",
> > +                                                   ad7944_spi_modes,
> > +                                                   ARRAY_SIZE(ad7944_spi_modes));
> > +       if (ret < 0) {
> > +               if (ret != -EINVAL)
> > +                       return dev_err_probe(dev, ret,
> > +                                            "getting adi,spi-mode property failed\n");
>
> > -               adc->spi_mode = ret;
> > -       } else {
>
> Actually we may even leave these unchanged
>
> >                 /* absence of adi,spi-mode property means default mode */
> >                 adc->spi_mode = AD7944_SPI_MODE_DEFAULT;
> > +       } else {
> > +               adc->spi_mode = ret;
> >         }
>
>        ret = device_property_match_property_string(dev, "adi,spi-mode",
>                                                    ad7944_spi_modes,
>
> ARRAY_SIZE(ad7944_spi_modes));
>        if (ret >= 0) {
>                adc->spi_mode = ret;
>        } else if (ret != -EINVAL) {
>                        return dev_err_probe(dev, ret,
>                                             "getting adi,spi-mode
> property failed\n");
>        } else {
>                /* absence of adi,spi-mode property means default mode */
>                adc->spi_mode = AD7944_SPI_MODE_DEFAULT;
>        }
>
> But I can admit this is not an often used approach.
>

I think Jonathan prefers to have the error path first, so I would like
to wait and see if he has an opinion here.