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authorGuenter Roeck <linux@roeck-us.net>2014-12-04 18:58:15 +0100
committerGuenter Roeck <linux@roeck-us.net>2014-12-05 19:18:02 +0100
commit4ad40cc568c5537de11092d3362f9cb287f915d9 (patch)
treed645f9b83c36b6aa231740ab1f8926f2158f7c99 /drivers/hwmon/lm75.c
parenthwmon: (gpio-fan) Add a shutdown handler to poweroff the fans (diff)
downloadlinux-4ad40cc568c5537de11092d3362f9cb287f915d9.tar.xz
linux-4ad40cc568c5537de11092d3362f9cb287f915d9.zip
hwmon: (lm75) Strengthen detect function
A chip returning 0x00 in all registers is erroneously detected as LM75. Check hysteresis and temperature limit registers and abort if both are 0 to reduce the likelyhood for this to happen. Reviewed-by: Rob Coulson <rob.coulson@gmail.com> Reviewed-by: Jean Delvare <jdelvare@suse.de> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Diffstat (limited to 'drivers/hwmon/lm75.c')
-rw-r--r--drivers/hwmon/lm75.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index f58439b817b5..6753fd940c76 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -415,6 +415,12 @@ static int lm75_detect(struct i2c_client *new_client,
|| i2c_smbus_read_byte_data(new_client, 7) != os)
return -ENODEV;
}
+ /*
+ * It is very unlikely that this is a LM75 if both
+ * hysteresis and temperature limit registers are 0.
+ */
+ if (hyst == 0 && os == 0)
+ return -ENODEV;
/* Addresses cycling */
for (i = 8; i <= 248; i += 40) {