linux-kernel - Re: [PATCH v2 04/12] iio: adc: ad7192: handle zero Avdd regulator value as error

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Date:   Wed, 12 May 2021 09:28:41 +0300
From:   Alexandru Ardelean <aardelean@...iqon.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        alexandru.tachici@...log.com, linux@...iqon.com
Subject: Re: [PATCH v2 04/12] iio: adc: ad7192: handle zero Avdd regulator
 value as error

On Tue, 11 May 2021 at 17:12, Jonathan Cameron <jic23@...nel.org> wrote:
>
> On Tue, 11 May 2021 10:18:23 +0300
> Alexandru Ardelean <aardelean@...iqon.com> wrote:
>
> > This change fixes a corner-case, where the returned voltage is actually
> > zero. This is also what patch ab0afa65bbc7 ("staging: iio: adc: ad7192:
> > fail probe on get_voltage") was trying to do.
> >
> > But as Jonathan pointed out, a zero-value would signal that the probe has
> > succeeded, putting the driver is a semi-initialized state.
> >
> > Fixes: ab0afa65bbc7 ("staging: iio: adc: ad7192: fail probe on get_voltage")
> > Cc: Alexandru Tachici <alexandru.tachici@...log.com>
> > Signed-off-by: Alexandru Ardelean <aardelean@...iqon.com>
>
> Given that voltage_uv == 1 would result in a situation no worse than
> for voltage_uv == 0 perhaps we should just change the following condition to
>
> if (voltage_uv >= 0)  ?

hmmm, you're right;
i think had some narrow vision about this;

will send a v3

>
> Jonathan
>
> > ---
> >  drivers/iio/adc/ad7192.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
> > index d3be67aa0522..79df54e0dc96 100644
> > --- a/drivers/iio/adc/ad7192.c
> > +++ b/drivers/iio/adc/ad7192.c
> > @@ -950,6 +950,11 @@ static int ad7192_probe(struct spi_device *spi)
> >       }
> >
> >       voltage_uv = regulator_get_voltage(st->avdd);
> > +     if (voltage_uv == 0) {
> > +             ret = -EINVAL;
> > +             dev_err(&spi->dev, "Zero value provided for AVdd supply\n");
> > +             goto error_disable_avdd;
> > +     }
> >
> >       if (voltage_uv > 0) {
> >               st->int_vref_mv = voltage_uv / 1000;
>