hwmon: (pmbus) Improve fan detection

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@ericsson.com>
Reviewed-by: Robert Coulson <robert.coulson@ericsson.com>
Cc: stable.kernel.org # 2.6.39

diff --git a/drivers/hwmon/pmbus.c b/drivers/hwmon/pmbus.c
index 98e2e28899e2cd24f07d2eac0095479745d23a1d..b0ea00b75f173556be047b9cba69359e1b512e00 100644 (file)
--- a/drivers/hwmon/pmbus.c
+++ b/drivers/hwmon/pmbus.c
@@ -47,12 +47,14 @@ static void pmbus_find_sensor_groups(struct i2c_client *client,
        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;