hwmon: (pmbus) Fix page count auto-detection.

BugLink: https://bugs.launchpad.net/bugs/1810947

commit e7c6a556 upstream.

Devices with compatible="pmbus" field have zero initial page count,
and pmbus_clear_faults() being called before the page count auto-
detection does not actually clear faults because it depends on the
page count. Non-cleared faults in its turn may fail the subsequent
page count auto-detection.

This patch fixes this problem by calling pmbus_clear_fault_page()
for currently set page and calling pmbus_clear_faults() after the
page count was detected.

Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Bazhenov <bazhenov.dn@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/hwmon/pmbus/pmbus.c

@@ -117,6 +117,8 @@ static int pmbus_identify(struct i2c_client *client,
 		} else {
 			info->pages = 1;
 		}
+
+		pmbus_clear_faults(client);
 	}
 
 	if (pmbus_check_byte_register(client, 0, PMBUS_VOUT_MODE)) {

drivers/hwmon/pmbus/pmbus_core.c

@@ -1759,7 +1759,10 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
 	if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK))
 		client->flags |= I2C_CLIENT_PEC;
 
-	pmbus_clear_faults(client);
+	if (data->info->pages)
+		pmbus_clear_faults(client);
+	else
+		pmbus_clear_fault_page(client, -1);
 
 	if (info->identify) {
 		ret = (*info->identify)(client, info);