linux-kernel - Re: [PATCH] iio: magnetometer: ak8974: Fix the error handling of ak8974

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Message-ID: <CACRpkdaFgB55HHR8a3vyVbZphu5fpguutBYemyVvGz=tcn6j+A@mail.gmail.com>
Date:   Thu, 21 Apr 2022 01:14:09 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Zheyu Ma <zheyuma97@...il.com>, lars@...afoo.de,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH] iio: magnetometer: ak8974: Fix the error handling of ak8974_probe()

On Sun, Apr 10, 2022 at 5:46 PM Jonathan Cameron <jic23@...nel.org> wrote:
> On Sat,  9 Apr 2022 11:48:48 +0800
> Zheyu Ma <zheyuma97@...il.com> wrote:
>
> > When the driver fail at devm_regmap_init_i2c(), we will get the
> > following splat:
> >
> > [  106.797388] WARNING: CPU: 4 PID: 413 at drivers/regulator/core.c:2257 _regulator_put+0x3ec/0x4e0
> > [  106.802183] RIP: 0010:_regulator_put+0x3ec/0x4e0
> > [  106.811237] Call Trace:
> > [  106.811515]  <TASK>
> > [  106.811695]  regulator_bulk_free+0x82/0xe0
> > [  106.812032]  devres_release_group+0x319/0x3d0
> > [  106.812425]  i2c_device_probe+0x766/0x940
> >
> > Fix this by disabling the regulators at the error path.
> >
> > Signed-off-by: Zheyu Ma <zheyuma97@...il.com>
> + CC Linus W as it's his driver.
>
> Fix looks correct to me, though the handling of runtime pm in here is
> probably more complex than it needs to be (and hence this odd error
> handling for this one place in the probe).

At the time I discussed how to do runtime pm with Ulf Hansson a lot
and I think it was the state of the art at that time. It might have
changed since.

> > ---
> >  drivers/iio/magnetometer/ak8974.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/iio/magnetometer/ak8974.c b/drivers/iio/magnetometer/ak8974.c
> > index e54feacfb980..84bbf7ccc887 100644
> > --- a/drivers/iio/magnetometer/ak8974.c
> > +++ b/drivers/iio/magnetometer/ak8974.c
> > @@ -862,6 +862,7 @@ static int ak8974_probe(struct i2c_client *i2c,
> >               dev_err(&i2c->dev, "failed to allocate register map\n");
> >               pm_runtime_put_noidle(&i2c->dev);
> >               pm_runtime_disable(&i2c->dev);
> > +             regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);

Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij