From: Guenter Roeck <linux@roeck-us.net>
Date: Thu, 4 Dec 2014 17:58:15 +0000 (-0800)
Subject: hwmon: (lm75) Strengthen detect function
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4ad40cc568c5537de11092d3362f9cb287f915d9;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

hwmon: (lm75) Strengthen detect function

A chip returning 0x00 in all registers is erroneously detected
as LM75. Check hysteresis and temperature limit registers and
abort if both are 0 to reduce the likelyhood for this to happen.

Reviewed-by: Rob Coulson <rob.coulson@gmail.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index f58439b817b5..6753fd940c76 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -415,6 +415,12 @@ static int lm75_detect(struct i2c_client *new_client,
 		 || i2c_smbus_read_byte_data(new_client, 7) != os)
 			return -ENODEV;
 	}
+	/*
+	 * It is very unlikely that this is a LM75 if both
+	 * hysteresis and temperature limit registers are 0.
+	 */
+	if (hyst == 0 && os == 0)
+		return -ENODEV;
 
 	/* Addresses cycling */
 	for (i = 8; i <= 248; i += 40) {