[PATCH 5.10 31/66] hwmon: (f71882fg) Fix negative temperature

Greg Kroah-Hartman
2022-05-16T19:53:26Z

From: Ji-Ze Hong (Peter Hong) <hpeter@gmail.com>

[ Upstream commit 4aaaaf0f279836f06d3b9d0ffeec7a1e1a04ceef ]

All temperature of Fintek superio hwmonitor that using 1-byte reg will use
2's complement.

In show_temp()
temp = data->temp[nr] * 1000;

When data->temp[nr] read as 255, it indicate -1C, but this code will report
255C to userspace. It'll be ok when change to:
temp = ((s8)data->temp[nr]) * 1000;

Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
Link: https://lore.kernel.org/r/20220418090706.6339-1-hpeter+linux_kernel@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/f71882fg.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/f71882fg.c b/drivers/hwmon/f71882fg.c
index 4dec793fd07d..94b35723ee7a 100644
--- a/drivers/hwmon/f71882fg.c
+++ b/drivers/hwmon/f71882fg.c
@@ -1577,8 +1577,9 @@ static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
temp *= 125;
if (sign)
temp -= 128000;
- } else
- temp = data->temp[nr] * 1000;
+ } else {
+ temp = ((s8)data->temp[nr]) * 1000;
+ }

return sprintf(buf, "%d\n", temp);
}
--
2.35.1