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authorDavid Fries <david@fries.net>2008-01-22 03:31:37 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-01-22 09:17:48 -0800
commit941ed3b53086697eac7449f3ab5d2c5ab3259de2 (patch)
treecd0192ab9a6ab906edc59be1ccf92df49b206c9a /drivers/w1/slaves/w1_therm.c
parentd384e35a25445bb60457b7dab8cffe178c6b7ecb (diff)
W1: w1_therm.c ds18b20 decode freezing temperatures correctly
Correct the decoding of negative C temperatures. The code did a binary OR of two bytes to make a 16 bit value, but assignd it to an integer. This caused the value to not be sign extended and to loose that it was a negative number in the assignment. Before the patch (in my freezer), w1_slave ed fe 4b 46 7f ff 03 10 e4 : crc=e4 YES ed fe 4b 46 7f ff 03 10 e4 t=4078 With the patch, e3 fe 4b 46 7f ff 0d 10 81 : crc=81 YES e3 fe 4b 46 7f ff 0d 10 81 t=-17 Signed-off-by: David Fries <david@fries.net> Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/w1/slaves/w1_therm.c')
-rw-r--r--drivers/w1/slaves/w1_therm.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index 4318935678c..feed89e733e 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -112,7 +112,7 @@ static struct w1_therm_family_converter w1_therm_families[] = {
static inline int w1_DS18B20_convert_temp(u8 rom[9])
{
- int t = (rom[1] << 8) | rom[0];
+ s16 t = (rom[1] << 8) | rom[0];
t /= 16;
return t;
}