hwmon: (tmp421) Fix temperature conversions

The low bits of temperature registers are status bits, they must be
masked out before converting the register values to temperatures.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Andre Prendel <andre.prendel@gmx.de>
Cc: stable@kernel.org

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
index a97e299b233b..bb9760d7e8b6 100644
--- a/drivers/hwmon/tmp421.c
+++ b/drivers/hwmon/tmp421.c
@@ -80,14 +80,16 @@ struct tmp421_data {
 
 static int temp_from_s16(s16 reg)
 {
-        int temp = reg;
+        /* Mask out status bits */
+        int temp = reg & ~0xf;
 
         return (temp * 1000 + 128) / 256;
 }
 
 static int temp_from_u16(u16 reg)
 {
-        int temp = reg;
+        /* Mask out status bits */
+        int temp = reg & ~0xf;
 
         /* Add offset for extended temperature range. */
         temp -= 64 * 256;