linux-kernel - [PATCH v3 3/3] hwmon: tmp401: bail-out from tmp401

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Message-Id: <1417711553-21311-4-git-send-email-bgolaszewski@baylibre.com>
Date:	Thu,  4 Dec 2014 17:45:53 +0100
From:	Bartosz Golaszewski <bgolaszewski@...libre.com>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Benoit Cousson <bcousson@...libre.com>,
	Patrick Titiano <ptitiano@...libre.com>,
	LM Sensors <lm-sensors@...sensors.org>,
	Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH v3 3/3] hwmon: tmp401: bail-out from tmp401_probe() in case of write errors

The return value of i2c_smbus_read_byte_data() is checked in
tmp401_init_client(), but only a warning is printed and the device is
registered anyway. This leads to devices being registered even if they
cannot be physically detected.

Bail-out from probe in case of write errors and notify the user.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
---
 drivers/hwmon/tmp401.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/hwmon/tmp401.c b/drivers/hwmon/tmp401.c
index ccd9938..f2182ee 100644
--- a/drivers/hwmon/tmp401.c
+++ b/drivers/hwmon/tmp401.c
@@ -615,10 +615,10 @@ static const struct attribute_group tmp432_group = {
  * Begin non sysfs callback code (aka Real code)
  */
 
-static void tmp401_init_client(struct tmp401_data *data,
-			       struct i2c_client *client)
+static int tmp401_init_client(struct tmp401_data *data,
+			      struct i2c_client *client)
 {
-	int config, config_orig;
+	int config, config_orig, status = 0;
 
 	/* Set the conversion rate to 2 Hz */
 	i2c_smbus_write_byte_data(client, TMP401_CONVERSION_RATE_WRITE, 5);
@@ -626,16 +626,18 @@ static void tmp401_init_client(struct tmp401_data *data,
 
 	/* Start conversions (disable shutdown if necessary) */
 	config = i2c_smbus_read_byte_data(client, TMP401_CONFIG_READ);
-	if (config < 0) {
-		dev_warn(&client->dev, "Initialization failed!\n");
-		return;
-	}
+	if (config < 0)
+		return config;
 
 	config_orig = config;
 	config &= ~TMP401_CONFIG_SHUTDOWN;
 
 	if (config != config_orig)
-		i2c_smbus_write_byte_data(client, TMP401_CONFIG_WRITE, config);
+		status = i2c_smbus_write_byte_data(client,
+						   TMP401_CONFIG_WRITE,
+						   config);
+
+	return status;
 }
 
 static int tmp401_detect(struct i2c_client *client,
@@ -718,7 +720,7 @@ static int tmp401_probe(struct i2c_client *client,
 	struct device *dev = &client->dev;
 	struct device *hwmon_dev;
 	struct tmp401_data *data;
-	int groups = 0;
+	int groups = 0, status;
 
 	data = devm_kzalloc(dev, sizeof(struct tmp401_data), GFP_KERNEL);
 	if (!data)
@@ -729,7 +731,9 @@ static int tmp401_probe(struct i2c_client *client,
 	data->kind = id->driver_data;
 
 	/* Initialize the TMP401 chip */
-	tmp401_init_client(data, client);
+	status = tmp401_init_client(data, client);
+	if (status < 0)
+		return status;
 
 	/* Register sysfs hooks */
 	data->groups[groups++] = &tmp401_group;
-- 
2.1.3

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