linux-kernel - Re: [PATCH v3 04/12] iio: adc: ad7192: handle zero Avdd regulator value

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Date:   Thu, 13 May 2021 12:11:46 +0300
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Lars-Peter Clausen <lars@...afoo.de>
Cc:     Alexandru Ardelean <aardelean@...iqon.com>,
        linux-iio <linux-iio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Alexandru Tachici <alexandru.tachici@...log.com>,
        linux@...iqon.com
Subject: Re: [PATCH v3 04/12] iio: adc: ad7192: handle zero Avdd regulator value

On Thu, May 13, 2021 at 10:43 AM Lars-Peter Clausen <lars@...afoo.de> wrote:
>
> On 5/12/21 7:49 PM, Alexandru Ardelean wrote:
> > This change fixes a corner-case, where for a zero regulator value, the
> > driver would exit early, initializing the driver only partially.
> > The driver would be in an unknown state.
> >
> > If the regulator value is zero, then the internal reference will be zero
> > (though that value will be zero for anything less than 1 millivolt).
> >
> > 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>
> > ---
> >   drivers/iio/adc/ad7192.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
> > index d3be67aa0522..9da394ad3868 100644
> > --- a/drivers/iio/adc/ad7192.c
> > +++ b/drivers/iio/adc/ad7192.c
> > @@ -951,7 +951,7 @@ static int ad7192_probe(struct spi_device *spi)
> >
> >       voltage_uv = regulator_get_voltage(st->avdd);
> >
> > -     if (voltage_uv > 0) {
> > +     if (voltage_uv >= 0) {
> >               st->int_vref_mv = voltage_uv / 1000;
> >       } else {
> >               ret = voltage_uv;
>
> More idiomatic would be to check for voltage_uv < 0.

sure;
makes sense
will re-spin

>
>      if (voltage_uv < 0) {
>          ret = voltage_uv;
>          dev_err(&spi->dev, "Device tree error, reference voltage
> undefined\n");
>          goto error_disable_avdd;
>      }
>
>      st->int_vref_mv = voltage_uv / 1000;
>