linux-kernel - [PATCH v2 2/2] platform/x86: dell-ddv: Fix temperature scaling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230218115318.20662-2-W_Armin@gmx.de>
Date:   Sat, 18 Feb 2023 12:53:18 +0100
From:   Armin Wolf <W_Armin@....de>
To:     hdegoede@...hat.com, markgross@...nel.org
Cc:     jdelvare@...e.com, linux@...ck-us.net,
        platform-driver-x86@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] platform/x86: dell-ddv: Fix temperature scaling

After using the built-in UEFI hardware diagnostics to compare
the measured battery temperature, i noticed that the temperature
is actually expressed in tenth degree kelvin, similar to the
SBS-Data standard. For example, a value of 2992 is displayed as
26 degrees celsius.
Fix the scaling so that the correct values are being displayed.

Tested on a Dell Inspiron 3505.

Fixes: a77272c16041 ("platform/x86: dell: Add new dell-wmi-ddv driver")
Signed-off-by: Armin Wolf <W_Armin@....de>
---
Changes in v2:
- Avoid unnecessary rounding
---
 drivers/platform/x86/dell/dell-wmi-ddv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c b/drivers/platform/x86/dell/dell-wmi-ddv.c
index eff4e9649faf..2750dee99c3e 100644
--- a/drivers/platform/x86/dell/dell-wmi-ddv.c
+++ b/drivers/platform/x86/dell/dell-wmi-ddv.c
@@ -17,7 +17,6 @@
 #include <linux/kernel.h>
 #include <linux/hwmon.h>
 #include <linux/kstrtox.h>
-#include <linux/math.h>
 #include <linux/math64.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -665,7 +664,8 @@ static ssize_t temp_show(struct device *dev, struct device_attribute *attr, char
 	if (ret < 0)
 		return ret;

-	return sysfs_emit(buf, "%d\n", DIV_ROUND_CLOSEST(value, 10));
+	/* Use 2731 instead of 2731.5 to avoid unnecessary rounding */
+	return sysfs_emit(buf, "%d\n", value - 2731);
 }

 static ssize_t eppid_show(struct device *dev, struct device_attribute *attr, char *buf)
--
2.30.2