linux-kernel - [PATCH 3/3] hwmon: (coretemp) Refine TjMax detection

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Date:	Sat,  9 Nov 2013 09:51:09 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Jean Delvare <khali@...ux-fr.org>,
	Fenghua Yu <fenghua.yu@...el.com>
Cc:	lm-sensors@...sensors.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 3/3] hwmon: (coretemp) Refine TjMax detection

Intel's turbostat code uses only 7 bits from MSR_IA32_TEMPERATURE_TARGET to
read TjMax, and also only accepts it if the reported temperature is at least
85 degrees C. Play safe and do the same.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/hwmon/coretemp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index cde4e47..310ce19 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -368,12 +368,12 @@ static int get_tjmax(struct cpuinfo_x86 *c, u32 id, struct device *dev)
 		if (cpu_has_tjmax(c))
 			dev_warn(dev, "Unable to read TjMax from CPU %u\n", id);
 	} else {
-		val = (eax >> 16) & 0xff;
+		val = (eax >> 16) & 0x7f;
 		/*
 		 * If the TjMax is not plausible, an assumption
 		 * will be used
 		 */
-		if (val) {
+		if (val >= 85) {
 			dev_dbg(dev, "TjMax is %d degrees C\n", val);
 			return val * 1000;
 		}
-- 
1.7.9.7

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