From: Guenter Roeck <linux@roeck-us.net>
Date: Thu, 8 Feb 2018 01:49:39 +0000 (-0800)
Subject: hwmon: (k10temp) Only apply temperature offset if result is positive
X-Git-Tag: v4.15.14~15
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1a0d6102cd024c2166e118d050a60157ba5a22f8;p=thirdparty%2Fkernel%2Fstable.git

hwmon: (k10temp) Only apply temperature offset if result is positive

commit aef17ca1271948ee57cc39b2493d31110cc42625 upstream.

A user reports a really bad temperature on Ryzen 1950X.

k10temp-pci-00cb
Adapter: PCI adapter
temp1: +4294948.3°C (high = +70.0°C)

This will happen if the temperature reported by the chip is lower than
the offset temperature. This has been seen in the field if "Sense MI Skew"
and/or "Sense MI Offset" BIOS parameters were set to unexpected values.
Let's report a temperature of 0 degrees C in that case.

Fixes: 1b50b776355f ("hwmon: (k10temp) Add support for temperature offsets")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/hwmon/k10temp.c b/drivers/hwmon/k10temp.c
index b960015cb073d..144ff80230613 100644
--- a/drivers/hwmon/k10temp.c
+++ b/drivers/hwmon/k10temp.c
@@ -128,7 +128,10 @@ static ssize_t temp1_input_show(struct device *dev,
 
 	data->read_tempreg(data->pdev, &regval);
 	temp = (regval >> 21) * 125;
-	temp -= data->temp_offset;
+	if (temp > data->temp_offset)
+		temp -= data->temp_offset;
+	else
+		temp = 0;
 
 	return sprintf(buf, "%u\n", temp);
 }