linux-kernel - Re: [PATCH v2] iio: dac: ad5380: Fix probe failure when no external reference is supplied

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Date:	Sun, 24 Jul 2016 11:03:30 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Paweł Grudziński <pgrudzinski@...nmailbox.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Michael Hennerich <Michael.Hennerich@...log.com>,
	Hartmut Knaack <knaack.h@....de>,
	Peter Meerwald <pmeerw@...erw.net>, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: dac: ad5380: Fix probe failure when no external
 reference is supplied

On 19/07/16 07:12, Paweł Grudziński wrote:
> From: Pawel Grudzinski <pgrudzinski@...nmailbox.org>
> 
> Driver fails to load when there is no external Vref regulator defined,
> leaving no way to use internal reference. ad5380_probe function tries to
> obtain regulator with demv_regulator_get and checks for error, in which
> case it would use internal reference. Even without "Vref" regulator defined
> devm_regulator_get returns dummy regulator which makes function omit use of
> internal reference and causes failure on regulator_get_voltage.
> 
> Replace demv_regulator_get with demv_regulator_get_optional, which returns
> error instead of dummy regulator if it does not find one which is specified
> by the caller to make ad5380_probe configure internal reference when no
> "Vref" regulator is supplied.
> 
> Initialize internal regulator only if returned error is ENODEV, otherwise
> propagate the error to the caller of probe.
> 
> Signed-off-by: Paweł Grudziński <pgrudzinski@...nmailbox.org>
> ---
> Changes in v2:
> - Add error type checking to enable internal reference only on ENODEV and
> return any other error to the caller.
> 
>  drivers/iio/dac/ad5380.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5380.c b/drivers/iio/dac/ad5380.c
> index 97d2c51..144cfdc 100644
> --- a/drivers/iio/dac/ad5380.c
> +++ b/drivers/iio/dac/ad5380.c
> @@ -401,7 +401,7 @@ static int ad5380_probe(struct device *dev, struct regmap *regmap,
>  	if (st->chip_info->int_vref == 2500)
>  		ctrl |= AD5380_CTRL_INT_VREF_2V5;
>  
> -	st->vref_reg = devm_regulator_get(dev, "vref");
> +	st->vref_reg = devm_regulator_get_optional(dev, "vref");
>  	if (!IS_ERR(st->vref_reg)) {
>  		ret = regulator_enable(st->vref_reg);
>  		if (ret) {
> @@ -416,8 +416,13 @@ static int ad5380_probe(struct device *dev, struct regmap *regmap,
>  
>  		st->vref = ret / 1000;
>  	} else {
> -		st->vref = st->chip_info->int_vref;
> -		ctrl |= AD5380_CTRL_INT_VREF_EN;
> +		if (PTR_ERR(st->vref_reg) == -ENODEV) {
> +			st->vref = st->chip_info->int_vref;
> +			ctrl |= AD5380_CTRL_INT_VREF_EN;
> +		} else {
> +			ret = st->vref_reg;
Autobuilder picked it up an issue.  This should be ret = PTR_ERR(st->vref_reg) I think?

Jonathan
> +			goto error_free_reg;
> +		}
>  	}
>  
>  	ret = regmap_write(st->regmap, AD5380_REG_SF_CTRL, ctrl);
>