linux-kernel - [PATCH] iio: magnetometer: ak8974: Fix runtime PM imbalance on error

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Date:   Sun, 24 May 2020 10:51:17 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn, kjlu@....edu
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] iio: magnetometer: ak8974: Fix runtime PM imbalance on error

When devm_regmap_init_i2c() returns an error code, a pairing
runtime PM usage counter decrement is needed to keep the
counter balanced. For error paths after ak8974_set_power(),
ak8974_detect() and ak8974_reset(), things are the same.

However, When iio_triggered_buffer_setup() returns an error
code, we don't need such a decrement because there is already
one before this call. Things are the same for other error paths
after it.

Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
---
 drivers/iio/magnetometer/ak8974.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/magnetometer/ak8974.c b/drivers/iio/magnetometer/ak8974.c
index d32996702110..c1bdb304eb9e 100644
--- a/drivers/iio/magnetometer/ak8974.c
+++ b/drivers/iio/magnetometer/ak8974.c
@@ -764,18 +764,24 @@ static int ak8974_probe(struct i2c_client *i2c,
 	ak8974->map = devm_regmap_init_i2c(i2c, &ak8974_regmap_config);
 	if (IS_ERR(ak8974->map)) {
 		dev_err(&i2c->dev, "failed to allocate register map\n");
+		pm_runtime_put_noidle(&i2c->dev);
+		pm_runtime_disable(&i2c->dev);
 		return PTR_ERR(ak8974->map);
 	}
 
 	ret = ak8974_set_power(ak8974, AK8974_PWR_ON);
 	if (ret) {
 		dev_err(&i2c->dev, "could not power on\n");
+		pm_runtime_put_noidle(&i2c->dev);
+		pm_runtime_disable(&i2c->dev);
 		goto power_off;
 	}
 
 	ret = ak8974_detect(ak8974);
 	if (ret) {
 		dev_err(&i2c->dev, "neither AK8974 nor AMI30x found\n");
+		pm_runtime_put_noidle(&i2c->dev);
+		pm_runtime_disable(&i2c->dev);
 		goto power_off;
 	}
 
@@ -786,6 +792,8 @@ static int ak8974_probe(struct i2c_client *i2c,
 	ret = ak8974_reset(ak8974);
 	if (ret) {
 		dev_err(&i2c->dev, "AK8974 reset failed\n");
+		pm_runtime_put_noidle(&i2c->dev);
+		pm_runtime_disable(&i2c->dev);
 		goto power_off;
 	}
 
@@ -851,7 +859,6 @@ static int ak8974_probe(struct i2c_client *i2c,
 cleanup_buffer:
 	iio_triggered_buffer_cleanup(indio_dev);
 disable_pm:
-	pm_runtime_put_noidle(&i2c->dev);
 	pm_runtime_disable(&i2c->dev);
 	ak8974_set_power(ak8974, AK8974_PWR_OFF);
 power_off:
-- 
2.17.1