linux-kernel - Re: [PATCH 5.10 036/530] iio:adc:ad7476: Fix remove handling

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Date:   Sun, 16 May 2021 08:28:00 +0300
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Pavel Machek <pavel@...x.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>, stable@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Michael Hennerich <michael.hennerich@...log.com>
Subject: Re: [PATCH 5.10 036/530] iio:adc:ad7476: Fix remove handling

On Sat, May 15, 2021 at 10:52 PM Pavel Machek <pavel@...x.de> wrote:
>
> Hi!
> >
> > commit 6baee4bd63f5fdf1716f88e95c21a683e94fe30d upstream.
> >
> > This driver was in an odd half way state between devm based cleanup
> > and manual cleanup (most of which was missing).
> > I would guess something went wrong with a rebase or similar.
> > Anyhow, this basically finishes the job as a precursor to improving
> > the regulator handling.
>
> I don't think this is correct:
>
> > --- a/drivers/iio/adc/ad7476.c
> > +++ b/drivers/iio/adc/ad7476.c
> > @@ -316,25 +316,15 @@ static int ad7476_probe(struct spi_devic
> >       spi_message_init(&st->msg);
> >       spi_message_add_tail(&st->xfer, &st->msg);
> >
> > -     ret = iio_triggered_buffer_setup(indio_dev, NULL,
> > -                     &ad7476_trigger_handler, NULL);
> > +     ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
> > +                                           &ad7476_trigger_handler, NULL);
> >       if (ret)
> > -             goto error_disable_reg;
> > +             return ret;
> >
> >       if (st->chip_info->reset)
> >               st->chip_info->reset(st);
> >
> > -     ret = iio_device_register(indio_dev);
> > -     if (ret)
> > -             goto error_ring_unregister;
> > -     return 0;
> > -
> > -error_ring_unregister:
> > -     iio_triggered_buffer_cleanup(indio_dev);
> > -error_disable_reg:
> > -     regulator_disable(st->reg);
> > -
>
> Regulator_disable is now removed, but we still use regulator_enable,
> and we still need to keep it balanced.

Yes, but that's what this block does:
    ret = devm_add_action_or_reset(&spi->dev, ad7476_reg_disable,
                       st);
    if (ret)
        return ret;

It registers a device-managed action to disable the regulator on error
or remove.
That ad7476_reg_disable() hook was implemented on commit:
4bb2b8f94ace3 ("iio: adc: ad7476: implement devm_add_action_or_reset")

But for some reason it wasn't done correctly, as this part [in this
patch] wasn't included in the 4bb2b8f94ace3  commit.

>
> > -     return ret;
> > +     return devm_iio_device_register(&spi->dev, indio_dev);
> >  }
>
> Best regards,
>                                                                 Pavel
>
> --
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany