Re: [PATCH 2/4] iio: st_sensors: remove st_sensors_power_disable() function

[Alexandru Ardelean <aardelean@deviqon.com>]

On Sat, 31 Jul 2021 at 20:34, Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Mon, 26 Jul 2021 10:14:02 +0300
> Alexandru Ardelean <aardelean@deviqon.com> wrote:
>
> > This change converts the st_sensors_power_enable() function to use
> > devm_add_action_or_reset() handlers to register regulator_disable hooks for
> > when the drivers get unloaded.
> >
> > The parent device of the IIO device object is used. This is based on the
> > assumption that all other devm_ calls in the ST sensors use this reference.
> >
> > This makes the st_sensors_power_disable() un-needed.
> > Removing this also changes unload order a bit, as all ST drivers would call
> > st_sensors_power_disable() first and iio_device_unregister() after that.
>
> Huh.  So currently the drivers turn the power off before calling
> iio_device_unregister()?
>
> That's a bad idea (turn off power when userspace is still available)
> and looks like a bug fix to me.  Perhaps the reorder should be pulled out as
> a precursor patch in case anyone wants to backport it?
>
> (note I initially thought you were going the other way and was just writing
>  a rant about breaking the order when I realised you were fixing it ;)

Probably the best advantage of devm_ functions .
Not needing to care about un-init order.

I hated debugging driver crashes when they were unloaded, usually
because the driver gets into a weird state.

I'll send a V2 with the re-order fixes in the front.

>
> >
> > Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
> > ---
> >  drivers/iio/accel/st_accel_i2c.c              | 13 +------
> >  drivers/iio/accel/st_accel_spi.c              | 13 +------
> >  .../iio/common/st_sensors/st_sensors_core.c   | 34 ++++++++-----------
> >  drivers/iio/gyro/st_gyro_i2c.c                | 13 +------
> >  drivers/iio/gyro/st_gyro_spi.c                | 13 +------
> >  drivers/iio/magnetometer/st_magn_i2c.c        | 13 +------
> >  drivers/iio/magnetometer/st_magn_spi.c        | 13 +------
> >  drivers/iio/pressure/st_pressure_i2c.c        | 13 +------
> >  drivers/iio/pressure/st_pressure_spi.c        | 13 +------
> >  include/linux/iio/common/st_sensors.h         |  2 --
> >  10 files changed, 23 insertions(+), 117 deletions(-)
> >
> > diff --git a/drivers/iio/accel/st_accel_i2c.c b/drivers/iio/accel/st_accel_i2c.c
> > index f711756e41e3..b377575efc41 100644
> > --- a/drivers/iio/accel/st_accel_i2c.c
> > +++ b/drivers/iio/accel/st_accel_i2c.c
> > @@ -177,24 +177,13 @@ static int st_accel_i2c_probe(struct i2c_client *client)
> >       if (ret)
> >               return ret;
> >
> > -     ret = st_accel_common_probe(indio_dev);
> > -     if (ret < 0)
> > -             goto st_accel_power_off;
> > -
> > -     return 0;
> > -
> > -st_accel_power_off:
> > -     st_sensors_power_disable(indio_dev);
> > -
> > -     return ret;
> > +     return st_accel_common_probe(indio_dev);
> >  }
> >
> >  static int st_accel_i2c_remove(struct i2c_client *client)
> >  {
> >       struct iio_dev *indio_dev = i2c_get_clientdata(client);
> >
> > -     st_sensors_power_disable(indio_dev);
> > -
> >       st_accel_common_remove(indio_dev);
> >
> >       return 0;
> > diff --git a/drivers/iio/accel/st_accel_spi.c b/drivers/iio/accel/st_accel_spi.c
> > index bb45d9ff95b8..4ca87e73bdb3 100644
> > --- a/drivers/iio/accel/st_accel_spi.c
> > +++ b/drivers/iio/accel/st_accel_spi.c
> > @@ -127,24 +127,13 @@ static int st_accel_spi_probe(struct spi_device *spi)
> >       if (err)
> >               return err;
> >
> > -     err = st_accel_common_probe(indio_dev);
> > -     if (err < 0)
> > -             goto st_accel_power_off;
> > -
> > -     return 0;
> > -
> > -st_accel_power_off:
> > -     st_sensors_power_disable(indio_dev);
> > -
> > -     return err;
> > +     return st_accel_common_probe(indio_dev);
> >  }
> >
> >  static int st_accel_spi_remove(struct spi_device *spi)
> >  {
> >       struct iio_dev *indio_dev = spi_get_drvdata(spi);
> >
> > -     st_sensors_power_disable(indio_dev);
> > -
> >       st_accel_common_remove(indio_dev);
> >
> >       return 0;
> > diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c b/drivers/iio/common/st_sensors/st_sensors_core.c
> > index 0bbb090b108c..a5a140de9a23 100644
> > --- a/drivers/iio/common/st_sensors/st_sensors_core.c
> > +++ b/drivers/iio/common/st_sensors/st_sensors_core.c
> > @@ -215,13 +215,19 @@ int st_sensors_set_axis_enable(struct iio_dev *indio_dev, u8 axis_enable)
> >  }
> >  EXPORT_SYMBOL(st_sensors_set_axis_enable);
> >
> > +static void st_reg_disable(void *reg)
> > +{
> > +     regulator_disable(reg);
> > +}
> > +
> >  int st_sensors_power_enable(struct iio_dev *indio_dev)
> >  {
> >       struct st_sensor_data *pdata = iio_priv(indio_dev);
> > +     struct device *parent = indio_dev->dev.parent;
> >       int err;
> >
> >       /* Regulators not mandatory, but if requested we should enable them. */
> > -     pdata->vdd = devm_regulator_get(indio_dev->dev.parent, "vdd");
> > +     pdata->vdd = devm_regulator_get(parent, "vdd");
> >       if (IS_ERR(pdata->vdd)) {
> >               dev_err(&indio_dev->dev, "unable to get Vdd supply\n");
> >               return PTR_ERR(pdata->vdd);
> > @@ -233,36 +239,26 @@ int st_sensors_power_enable(struct iio_dev *indio_dev)
> >               return err;
> >       }
> >
> > -     pdata->vdd_io = devm_regulator_get(indio_dev->dev.parent, "vddio");
> > +     err = devm_add_action_or_reset(parent, st_reg_disable, pdata->vdd);
> > +     if (err)
> > +             return err;
> > +
> > +     pdata->vdd_io = devm_regulator_get(parent, "vddio");
> >       if (IS_ERR(pdata->vdd_io)) {
> >               dev_err(&indio_dev->dev, "unable to get Vdd_IO supply\n");
> > -             err = PTR_ERR(pdata->vdd_io);
> > -             goto st_sensors_disable_vdd;
> > +             return PTR_ERR(pdata->vdd_io);
> >       }
> >       err = regulator_enable(pdata->vdd_io);
> >       if (err != 0) {
> >               dev_warn(&indio_dev->dev,
> >                        "Failed to enable specified Vdd_IO supply\n");
> > -             goto st_sensors_disable_vdd;
> > +             return err;
> >       }
> >
> > -     return 0;
> > -
> > -st_sensors_disable_vdd:
> > -     regulator_disable(pdata->vdd);
> > -     return err;
> > +     return devm_add_action_or_reset(parent, st_reg_disable, pdata->vdd_io);
> >  }
> >  EXPORT_SYMBOL(st_sensors_power_enable);
> >
> > -void st_sensors_power_disable(struct iio_dev *indio_dev)
> > -{
> > -     struct st_sensor_data *pdata = iio_priv(indio_dev);
> > -
> > -     regulator_disable(pdata->vdd);
> > -     regulator_disable(pdata->vdd_io);
> > -}
> > -EXPORT_SYMBOL(st_sensors_power_disable);
> > -
> >  static int st_sensors_set_drdy_int_pin(struct iio_dev *indio_dev,
> >                                       struct st_sensors_platform_data *pdata)
> >  {
> > diff --git a/drivers/iio/gyro/st_gyro_i2c.c b/drivers/iio/gyro/st_gyro_i2c.c
> > index 3ef86e16ee65..0bd80dfd389f 100644
> > --- a/drivers/iio/gyro/st_gyro_i2c.c
> > +++ b/drivers/iio/gyro/st_gyro_i2c.c
> > @@ -90,24 +90,13 @@ static int st_gyro_i2c_probe(struct i2c_client *client,
> >       if (err)
> >               return err;
> >
> > -     err = st_gyro_common_probe(indio_dev);
> > -     if (err < 0)
> > -             goto st_gyro_power_off;
> > -
> > -     return 0;
> > -
> > -st_gyro_power_off:
> > -     st_sensors_power_disable(indio_dev);
> > -
> > -     return err;
> > +     return st_gyro_common_probe(indio_dev);
> >  }
> >
> >  static int st_gyro_i2c_remove(struct i2c_client *client)
> >  {
> >       struct iio_dev *indio_dev = i2c_get_clientdata(client);
> >
> > -     st_sensors_power_disable(indio_dev);
> > -
> >       st_gyro_common_remove(indio_dev);
> >
> >       return 0;
> > diff --git a/drivers/iio/gyro/st_gyro_spi.c b/drivers/iio/gyro/st_gyro_spi.c
> > index 41d835493347..f74b09fa5cde 100644
> > --- a/drivers/iio/gyro/st_gyro_spi.c
> > +++ b/drivers/iio/gyro/st_gyro_spi.c
> > @@ -94,24 +94,13 @@ static int st_gyro_spi_probe(struct spi_device *spi)
> >       if (err)
> >               return err;
> >
> > -     err = st_gyro_common_probe(indio_dev);
> > -     if (err < 0)
> > -             goto st_gyro_power_off;
> > -
> > -     return 0;
> > -
> > -st_gyro_power_off:
> > -     st_sensors_power_disable(indio_dev);
> > -
> > -     return err;
> > +     return st_gyro_common_probe(indio_dev);
> >  }
> >
> >  static int st_gyro_spi_remove(struct spi_device *spi)
> >  {
> >       struct iio_dev *indio_dev = spi_get_drvdata(spi);
> >
> > -     st_sensors_power_disable(indio_dev);
> > -
> >       st_gyro_common_remove(indio_dev);
> >
> >       return 0;
> > diff --git a/drivers/iio/magnetometer/st_magn_i2c.c b/drivers/iio/magnetometer/st_magn_i2c.c
> > index 2dfe4ee99591..0a5117dffcf4 100644
> > --- a/drivers/iio/magnetometer/st_magn_i2c.c
> > +++ b/drivers/iio/magnetometer/st_magn_i2c.c
> > @@ -86,24 +86,13 @@ static int st_magn_i2c_probe(struct i2c_client *client,
> >       if (err)
> >               return err;
> >
> > -     err = st_magn_common_probe(indio_dev);
> > -     if (err < 0)
> > -             goto st_magn_power_off;
> > -
> > -     return 0;
> > -
> > -st_magn_power_off:
> > -     st_sensors_power_disable(indio_dev);
> > -
> > -     return err;
> > +     return st_magn_common_probe(indio_dev);
> >  }
> >
> >  static int st_magn_i2c_remove(struct i2c_client *client)
> >  {
> >       struct iio_dev *indio_dev = i2c_get_clientdata(client);
> >
> > -     st_sensors_power_disable(indio_dev);
> > -
> >       st_magn_common_remove(indio_dev);
> >
> >       return 0;
> > diff --git a/drivers/iio/magnetometer/st_magn_spi.c b/drivers/iio/magnetometer/st_magn_spi.c
> > index fba978796395..1f3bf02b24e0 100644
> > --- a/drivers/iio/magnetometer/st_magn_spi.c
> > +++ b/drivers/iio/magnetometer/st_magn_spi.c
> > @@ -80,24 +80,13 @@ static int st_magn_spi_probe(struct spi_device *spi)
> >       if (err)
> >               return err;
> >
> > -     err = st_magn_common_probe(indio_dev);
> > -     if (err < 0)
> > -             goto st_magn_power_off;
> > -
> > -     return 0;
> > -
> > -st_magn_power_off:
> > -     st_sensors_power_disable(indio_dev);
> > -
> > -     return err;
> > +     return st_magn_common_probe(indio_dev);
> >  }
> >
> >  static int st_magn_spi_remove(struct spi_device *spi)
> >  {
> >       struct iio_dev *indio_dev = spi_get_drvdata(spi);
> >
> > -     st_sensors_power_disable(indio_dev);
> > -
> >       st_magn_common_remove(indio_dev);
> >
> >       return 0;
> > diff --git a/drivers/iio/pressure/st_pressure_i2c.c b/drivers/iio/pressure/st_pressure_i2c.c
> > index 52fa98f24478..afeeab485c0d 100644
> > --- a/drivers/iio/pressure/st_pressure_i2c.c
> > +++ b/drivers/iio/pressure/st_pressure_i2c.c
> > @@ -103,24 +103,13 @@ static int st_press_i2c_probe(struct i2c_client *client,
> >       if (ret)
> >               return ret;
> >
> > -     ret = st_press_common_probe(indio_dev);
> > -     if (ret < 0)
> > -             goto st_press_power_off;
> > -
> > -     return 0;
> > -
> > -st_press_power_off:
> > -     st_sensors_power_disable(indio_dev);
> > -
> > -     return ret;
> > +     return st_press_common_probe(indio_dev);
> >  }
> >
> >  static int st_press_i2c_remove(struct i2c_client *client)
> >  {
> >       struct iio_dev *indio_dev = i2c_get_clientdata(client);
> >
> > -     st_sensors_power_disable(indio_dev);
> > -
> >       st_press_common_remove(indio_dev);
> >
> >       return 0;
> > diff --git a/drivers/iio/pressure/st_pressure_spi.c b/drivers/iio/pressure/st_pressure_spi.c
> > index ee393df54cee..834ad6d40a70 100644
> > --- a/drivers/iio/pressure/st_pressure_spi.c
> > +++ b/drivers/iio/pressure/st_pressure_spi.c
> > @@ -86,24 +86,13 @@ static int st_press_spi_probe(struct spi_device *spi)
> >       if (err)
> >               return err;
> >
> > -     err = st_press_common_probe(indio_dev);
> > -     if (err < 0)
> > -             goto st_press_power_off;
> > -
> > -     return 0;
> > -
> > -st_press_power_off:
> > -     st_sensors_power_disable(indio_dev);
> > -
> > -     return err;
> > +     return st_press_common_probe(indio_dev);
> >  }
> >
> >  static int st_press_spi_remove(struct spi_device *spi)
> >  {
> >       struct iio_dev *indio_dev = spi_get_drvdata(spi);
> >
> > -     st_sensors_power_disable(indio_dev);
> > -
> >       st_press_common_remove(indio_dev);
> >
> >       return 0;
> > diff --git a/include/linux/iio/common/st_sensors.h b/include/linux/iio/common/st_sensors.h
> > index e74b55244f35..fc90c202d15e 100644
> > --- a/include/linux/iio/common/st_sensors.h
> > +++ b/include/linux/iio/common/st_sensors.h
> > @@ -293,8 +293,6 @@ int st_sensors_set_axis_enable(struct iio_dev *indio_dev, u8 axis_enable);
> >
> >  int st_sensors_power_enable(struct iio_dev *indio_dev);
> >
> > -void st_sensors_power_disable(struct iio_dev *indio_dev);
> > -
> >  int st_sensors_debugfs_reg_access(struct iio_dev *indio_dev,
> >                                 unsigned reg, unsigned writeval,
> >                                 unsigned *readval);
>