[12/70] hwmon: (pmbus) Improve fan detection

[Greg KH]

2.6.39-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>

commit 81ae68142a0483b3791cba99eab268859858f508 upstream.

Some PMBus devices return no error when reading fan speed registers, but don't
really support fans. Strengthen fan detection by also checking if fan
configuration registers exist.

Signed-off-by: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
Reviewed-by: Robert Coulson <robert.coulson@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/hwmon/pmbus.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/hwmon/pmbus.c
+++ b/drivers/hwmon/pmbus.c
@@ -47,12 +47,14 @@ static void pmbus_find_sensor_groups(str
 	if (info->func[0]
 	    && pmbus_check_byte_register(client, 0, PMBUS_STATUS_INPUT))
 		info->func[0] |= PMBUS_HAVE_STATUS_INPUT;
-	if (pmbus_check_word_register(client, 0, PMBUS_READ_FAN_SPEED_1)) {
+	if (pmbus_check_byte_register(client, 0, PMBUS_FAN_CONFIG_12) &&
+	    pmbus_check_word_register(client, 0, PMBUS_READ_FAN_SPEED_1)) {
 		info->func[0] |= PMBUS_HAVE_FAN12;
 		if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_FAN_12))
 			info->func[0] |= PMBUS_HAVE_STATUS_FAN12;
 	}
-	if (pmbus_check_word_register(client, 0, PMBUS_READ_FAN_SPEED_3)) {
+	if (pmbus_check_byte_register(client, 0, PMBUS_FAN_CONFIG_34) &&
+	    pmbus_check_word_register(client, 0, PMBUS_READ_FAN_SPEED_3)) {
 		info->func[0] |= PMBUS_HAVE_FAN34;
 		if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_FAN_34))
 			info->func[0] |= PMBUS_HAVE_STATUS_FAN34;


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