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Subject[PATCH 4.19 057/109] hwmon: (scpi-hwmon) shows the negative temperature properly
Date
From: Riwen Lu <luriwen@kylinos.cn>

[ Upstream commit 78d13552346289bad4a9bf8eabb5eec5e5a321a5 ]

The scpi hwmon shows the sub-zero temperature in an unsigned integer,
which would confuse the users when the machine works in low temperature
environment. This shows the sub-zero temperature in an signed value and
users can get it properly from sensors.

Signed-off-by: Riwen Lu <luriwen@kylinos.cn>
Tested-by: Xin Chen <chenxin@kylinos.cn>
Link: https://lore.kernel.org/r/20210604030959.736379-1-luriwen@kylinos.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/scpi-hwmon.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/hwmon/scpi-hwmon.c b/drivers/hwmon/scpi-hwmon.c
index 7e49da50bc69..562f3e287297 100644
--- a/drivers/hwmon/scpi-hwmon.c
+++ b/drivers/hwmon/scpi-hwmon.c
@@ -107,6 +107,15 @@ scpi_show_sensor(struct device *dev, struct device_attribute *attr, char *buf)

scpi_scale_reading(&value, sensor);

+ /*
+ * Temperature sensor values are treated as signed values based on
+ * observation even though that is not explicitly specified, and
+ * because an unsigned u64 temperature does not really make practical
+ * sense especially when the temperature is below zero degrees Celsius.
+ */
+ if (sensor->info.class == TEMPERATURE)
+ return sprintf(buf, "%lld\n", (s64)value);
+
return sprintf(buf, "%llu\n", value);
}

--
2.30.2
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