hwmon: (pmbus) Improve auto-detection of temperature status register

It is possible that a PMBus device supports the READ_TEMPERATURE2 and/or
READ_TEMPERATURE3 registers but does not support READ_TEMPERATURE1.
Improve temperature status register detection to address this condition.

Reported-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Cc: stable@kernel.org # 2.6.39+

drivers/hwmon/pmbus.c

@@ -59,16 +59,17 @@ static void pmbus_find_sensor_groups(struct i2c_client *client,
 		if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_FAN_34))
 			info->func[0] |= PMBUS_HAVE_STATUS_FAN34;
 	}
-	if (pmbus_check_word_register(client, 0, PMBUS_READ_TEMPERATURE_1)) {
+	if (pmbus_check_word_register(client, 0, PMBUS_READ_TEMPERATURE_1))
 		info->func[0] |= PMBUS_HAVE_TEMP;
-		if (pmbus_check_byte_register(client, 0,
-					      PMBUS_STATUS_TEMPERATURE))
-			info->func[0] |= PMBUS_HAVE_STATUS_TEMP;
-	}
 	if (pmbus_check_word_register(client, 0, PMBUS_READ_TEMPERATURE_2))
 		info->func[0] |= PMBUS_HAVE_TEMP2;
 	if (pmbus_check_word_register(client, 0, PMBUS_READ_TEMPERATURE_3))
 		info->func[0] |= PMBUS_HAVE_TEMP3;
+	if (info->func[0] & (PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2
+			     | PMBUS_HAVE_TEMP3)
+	    && pmbus_check_byte_register(client, 0,
+					 PMBUS_STATUS_TEMPERATURE))
+			info->func[0] |= PMBUS_HAVE_STATUS_TEMP;
 
 	/* Sensors detected on all pages */
 	for (page = 0; page < info->pages; page++) {