From 07c16ad7fe6dd28e2054d6f7fee3c7d043c4e8da Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Mon, 23 Oct 2017 17:36:03 -0700 Subject: [PATCH] hwmon: (tmp102) Fix first temperature reading Commit f4b47bd3c135 ("hwmon: (tmp102) Improve handling of initial read delay") reduced the initial temperature read delay and made it dependent on the chip's shutdown mode. If the chip was not in shutdown mode at probe, the read delay no longer applies. This ignores the fact that the chip initialization changes the temperature sensor resolution, and that the temperature register values change when the resolution is changed. As a result, the reported temperature is twice as high as the real temperature until the first temperature conversion after the configuration change is complete. This can result in unexpected behavior and, worst case, in a system shutdown. To fix the problem, let's just always wait for a conversion to complete before reporting a temperature. Fixes: f4b47bd3c135 ("hwmon: (tmp102) Improve handling of initial read delay") Link: https://bugzilla.kernel.org/show_bug.cgi?id=197167 Reported-by: Ralf Goebel Cc: Ralf Goebel Reviewed-by: Jean Delvare Signed-off-by: Guenter Roeck --- drivers/hwmon/tmp102.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/drivers/hwmon/tmp102.c b/drivers/hwmon/tmp102.c index 5eafbaada7958..dfc40c740d07b 100644 --- a/drivers/hwmon/tmp102.c +++ b/drivers/hwmon/tmp102.c @@ -268,14 +268,11 @@ static int tmp102_probe(struct i2c_client *client, return err; } - tmp102->ready_time = jiffies; - if (tmp102->config_orig & TMP102_CONF_SD) { - /* - * Mark that we are not ready with data until the first - * conversion is complete - */ - tmp102->ready_time += msecs_to_jiffies(CONVERSION_TIME_MS); - } + /* + * Mark that we are not ready with data until the first + * conversion is complete + */ + tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS); hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, tmp102, -- 2.39.5