Re: [PATCH 1/6 v2] iio: magn: ak8975: fix regulator usage

[Jonathan Cameron <jic23@kernel.org>]

On 24/06/16 10:11, Linus Walleij wrote:
> IS_ERR_OR_NULL() should never be used with regulators because
> a NULL pointer may be a perfectly valid dummy regulator
> 
> We should always succeed to fetch and enable a regulator, but
> it may be a dummy. That is fine, so bail out for any real
> errors or probe deferrals
> 
> Include the error code in the warning print so we know what
> kind of problem we're dealing with (for example it is nice to
> see if it is a probe deferral).
> 
> As we will bail out of probe if the regulator is erroneous,
> just issue regulator_disable() on the poweroff path: it will
> succeed.
> 
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Lars-Peter Clausen Lars-Peter Clausen <lars@metafoo.de>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Umm. Linus - something went wrong here... See below...
> ---
> ChangeLog v1->v2:
> - No changes
> ---
>  drivers/iio/magnetometer/ak8975.c | 22 ++--------------------
>  1 file changed, 2 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
> index e0e43f497f40..05e9d5041e7a 100644
> --- a/drivers/iio/magnetometer/ak8975.c
> +++ b/drivers/iio/magnetometer/ak8975.c
> @@ -390,10 +390,8 @@ static int ak8975_power_on(struct i2c_client *client)
>  	int ret;
>  
>  	data->vdd = devm_regulator_get(&client->dev, "vdd");
> -	if (IS_ERR_OR_NULL(data->vdd)) {
> +	if (IS_ERR(data->vdd)) {
>  		ret = PTR_ERR(data->vdd);
> -		if (ret == -ENODEV)
> -			ret = 0;
>  	} else {
>  		ret = regulator_enable(data->vdd);
>  	}
> @@ -402,21 +400,6 @@ static int ak8975_power_on(struct i2c_client *client)
>  			 "Failed to enable specified Vdd supply\n");
>  		return ret;
>  	}

Where did the next block come from?  You introduce one of these in
the following patch, but there isn't one currently in the driver.
> -
> -	data->vid = devm_regulator_get(&client->dev, "vid");
> -	if (IS_ERR_OR_NULL(data->vid)) {
> -		ret = PTR_ERR(data->vdd);
> -		if (ret == -ENODEV)
> -			ret = 0;
> -	} else {
> -		ret = regulator_enable(data->vdd);
> -	}
> -	if (ret) {
> -		dev_warn(&client->dev,
> -			 "Failed to enable specified Vid supply\n");
> -		return ret;
> -	}
> -	return 0;
>  }
>  
>  /* Disable attached power regulator if any. */
> @@ -425,8 +408,7 @@ static void ak8975_power_off(const struct i2c_client *client)
>  	const struct iio_dev *indio_dev = i2c_get_clientdata(client);
>  	const struct ak8975_data *data = iio_priv(indio_dev);
>  
> -	if (!IS_ERR_OR_NULL(data->vdd))
> -		regulator_disable(data->vdd);
> +	regulator_disable(data->vdd);
>  }
>  
>  /*
>