Re: [PATCH 01/28] iio: gyro: fxa210002c: Balance runtime pm + use pm_runtime_resume_and_get().

[Mauro Carvalho Chehab <mchehab+huawei@kernel.org>]

Em Wed, 12 May 2021 15:22:43 +0200
Mauro Carvalho Chehab <mchehab+huawei@kernel.org> escreveu:

> Em Sun,  9 May 2021 12:33:27 +0100
> Jonathan Cameron <jic23@kernel.org> escreveu:
> 
> > From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > 
> > In both the probe() error path and remove() pm_runtime_put_noidle()
> > is called which will decrement the runtime pm reference count.
> > However, there is no matching function to have raised the reference count.
> > Not this isn't a fix as the runtime pm core will stop the reference count
> > going negative anyway.
> > 
> > An alternative would have been to raise the count in these paths, but
> > it is not clear why that would be necessary.
> > 
> > Whilst we are here replace some boilerplate with pm_runtime_resume_and_get()
> > Found using coccicheck script under review at:
> > https://lore.kernel.org/lkml/20210427141946.2478411-1-Julia.Lawall@inria.fr/
> > 
> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > Cc: Rui Miguel Silva <rui.silva@linaro.org>  
> 
> LGTM.
> 
> Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Hmm...not quite...

> > diff --git a/drivers/iio/gyro/fxas21002c_core.c b/drivers/iio/gyro/fxas21002c_core.c
> > index 5af7b48ff01a..539585b0d300 100644
> > --- a/drivers/iio/gyro/fxas21002c_core.c
> > +++ b/drivers/iio/gyro/fxas21002c_core.c
> > @@ -366,14 +366,7 @@ static int fxas21002c_write(struct fxas21002c_data *data,
> >  
> >  static int  fxas21002c_pm_get(struct fxas21002c_data *data)
> >  {
> > -	struct device *dev = regmap_get_device(data->regmap);
> > -	int ret;
> > -
> > -	ret = pm_runtime_get_sync(dev);
> > -	if (ret < 0)
> > -		pm_runtime_put_noidle(dev);
> > -
> > -	return ret;
> > +	return pm_runtime_resume_and_get(regmap_get_device(data->regmap));
> >  }

fxas21002c_temp_get() and fxas21002c_axis_get() seem to be
missing a pm_runtime_put*() if something gets wrong at
regmap_field_read(), e. g.:

static int fxas21002c_axis_get(struct fxas21002c_data *data,
                               int index, int *val)
{
        struct device *dev = regmap_get_device(data->regmap);
        __be16 axis_be;
        int ret;

        mutex_lock(&data->lock);
        ret = fxas21002c_pm_get(data);
        if (ret < 0)
                goto data_unlock;

        ret = regmap_bulk_read(data->regmap, FXAS21002C_AXIS_TO_REG(index),
                               &axis_be, sizeof(axis_be));
        if (ret < 0) {
                dev_err(dev, "failed to read axis: %d: %d\n", index, ret);
+		fxas21002c_pm_put(data);
                goto data_unlock;
        }

	*val = sign_extend32(be16_to_cpu(axis_be), 15);

        ret = fxas21002c_pm_put(data);
        if (ret < 0)
                goto data_unlock;

        ret = IIO_VAL_INT;

data_unlock:
	mutex_unlock(&data->lock);

        return ret;
}

Thanks,
Mauro