linux-kernel - Re: [PATCH] media: i2c: dw9714: Register a callback to disable the regulator

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Date:   Thu, 14 Apr 2022 10:35:42 +0800
From:   Zheyu Ma <zheyuma97@...il.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     mchehab@...nel.org, linux-media@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] media: i2c: dw9714: Register a callback to disable the regulator

On Wed, Apr 13, 2022 at 8:09 PM Sakari Ailus
<sakari.ailus@...ux.intel.com> wrote:
>
> Hi Zheyu,
>
> Thanks for the patch.
>
> On Sat, Apr 09, 2022 at 10:09:39PM +0800, Zheyu Ma wrote:
> > When the driver fails to probe, we will get the following splat:
> >
> > [   59.305988] ------------[ cut here ]------------
> > [   59.306417] WARNING: CPU: 2 PID: 395 at drivers/regulator/core.c:2257 _regulator_put+0x3ec/0x4e0
> > [   59.310345] RIP: 0010:_regulator_put+0x3ec/0x4e0
> > [   59.318362] Call Trace:
> > [   59.318582]  <TASK>
> > [   59.318765]  regulator_put+0x1f/0x30
> > [   59.319058]  devres_release_group+0x319/0x3d0
> > [   59.319420]  i2c_device_probe+0x766/0x940
> >
> > Fix this by adding a callback that will deal with the disabling when the
> > driver fails to probe.
> >
> > Signed-off-by: Zheyu Ma <zheyuma97@...il.com>
> > ---
> >  drivers/media/i2c/dw9714.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c
> > index cd7008ad8f2f..eccd05fc50c7 100644
> > --- a/drivers/media/i2c/dw9714.c
> > +++ b/drivers/media/i2c/dw9714.c
> > @@ -137,6 +137,13 @@ static int dw9714_init_controls(struct dw9714_device *dev_vcm)
> >       return hdl->error;
> >  }
> >
> > +static void dw9714_disable_regulator(void *arg)
> > +{
> > +     struct dw9714_device *dw9714_dev = arg;
> > +
> > +     regulator_disable(dw9714_dev->vcc);
> > +}
> > +
> >  static int dw9714_probe(struct i2c_client *client)
> >  {
> >       struct dw9714_device *dw9714_dev;
> > @@ -157,6 +164,10 @@ static int dw9714_probe(struct i2c_client *client)
> >               return rval;
> >       }
> >
> > +     rval = devm_add_action_or_reset(&client->dev, dw9714_disable_regulator, dw9714_dev);
> > +     if (rval)
> > +             return rval;
> > +
> >       v4l2_i2c_subdev_init(&dw9714_dev->sd, client, &dw9714_ops);
> >       dw9714_dev->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE |
> >                               V4L2_SUBDEV_FL_HAS_EVENTS;
>
> Could you instead disable the regulator in error handling in the probe
> function?

OK, I will send a v2 patch.

Zheyu Ma