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

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Date:	Thu, 14 Jul 2016 01:32:01 +0200
From:	Paweł Grudziński 
	<pgrudzinski@...nmailbox.org>
To:	Lars-Peter Clausen <lars@...afoo.de>,
	Michael Hennerich <Michael.Hennerich@...log.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Peter Meerwald <pmeerw@...erw.net>, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc:	Pawel Grudzinski <pgrudzinski@...nmailbox.org>
Subject: [PATCH] iio: ad5380: Fix probe failure when no external reference is supplied

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.

Signed-off-by: Paweł Grudziński <pgrudzinski@...nmailbox.org>
---
There are couple more places where I suspect similar issue with devices
having integrated reference, but I am sending this one because I tested it
with hardware. If this gets accepted, I will look through other drivers
obtaining Vref in same manner.

 drivers/iio/dac/ad5380.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/dac/ad5380.c b/drivers/iio/dac/ad5380.c
index 97d2c51..257d455 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) {
-- 
Best regards,

Paweł Grudziński