From d01b847c5cd070895c4ba178c85cd068a95cf7cd Mon Sep 17 00:00:00 2001
From: Larry Johnson <lrj@acm.org>
Date: Thu, 21 Feb 2008 13:58:16 -0500
Subject: [PATCH] LM75 bug fix for negative temperatures
When the LM75 temperature sensor measures a temperature below 0 C, the
current driver does not perform sign extension, so the result returned is
256 C too high. This patch fixes the problem.
Signed-off-by: Larry Johnson <lrj@acm.org>
---
drivers/hwmon/lm75.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index 63f3b7551e..e29b29440f 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -179,7 +179,13 @@ int dtt_init (void)
int dtt_get_temp(int sensor)
{
- return (dtt_read(sensor, DTT_READ_TEMP) / 256);
+ int const ret = dtt_read(sensor, DTT_READ_TEMP);
+
+ if (ret < 0) {
+ printf("DTT temperature read failed.\n");
+ return 0;
+ }
+ return (int)((int16_t) ret / 256);
} /* dtt_get_temp() */
#endif /* CONFIG_DTT_LM75 */
--
2.39.5