linux-kernel - [PATCH] i8k: Ignore temperature sensors which report invalid values

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Date:	Sun, 19 Oct 2014 16:46:54 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Guenter Roeck <linux@...ck-us.net>, Arnd Bergmann <arnd@...db.de>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Steven Honeyman <stevenhoneyman@...il.com>,
	Pali Rohár <pali.rohar@...il.com>
Subject: [PATCH] i8k: Ignore temperature sensors which report invalid values

On some machines some temperature sensors report too high values which are
invalid. When value is invalid function i8k_get_temp() returns previous
value and at next call it returns I8K_MAX_TEMP.

With this patch also firt i8k_get_temp() call returns I8K_MAX_TEMP and
i8k_init_hwmon() will ignore all sensor ids which report incorrect values.

Signed-off-by: Pali Rohár <pali.rohar@...il.com>
---
 drivers/char/i8k.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
index 7272b08..bc327fa 100644
--- a/drivers/char/i8k.c
+++ b/drivers/char/i8k.c
@@ -298,7 +298,7 @@ static int i8k_get_temp(int sensor)
 	int temp;
 
 #ifdef I8K_TEMPERATURE_BUG
-	static int prev[4];
+	static int prev[4] = { I8K_MAX_TEMP, I8K_MAX_TEMP, I8K_MAX_TEMP, I8K_MAX_TEMP };
 #endif
 	regs.ebx = sensor & 0xff;
 	rc = i8k_smm(&regs);
@@ -610,17 +610,17 @@ static int __init i8k_init_hwmon(void)
 
 	/* CPU temperature attributes, if temperature reading is OK */
 	err = i8k_get_temp(0);
-	if (err >= 0)
+	if (err >= 0 && err < I8K_MAX_TEMP)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP1;
 	/* check for additional temperature sensors */
 	err = i8k_get_temp(1);
-	if (err >= 0)
+	if (err >= 0 && err < I8K_MAX_TEMP)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP2;
 	err = i8k_get_temp(2);
-	if (err >= 0)
+	if (err >= 0 && err < I8K_MAX_TEMP)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP3;
 	err = i8k_get_temp(3);
-	if (err >= 0)
+	if (err >= 0 && err < I8K_MAX_TEMP)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP4;
 
 	/* Left fan attributes, if left fan is present */
-- 
1.7.9.5

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