soundwire: bus: check first if Slaves become UNATTACHED

Before checking for the presence of Device0, we first need to clean-up
the internal state of Slaves that are no longer attached.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200110215731.30747-7-pierre-louis.bossart@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/bus.c

@@ -979,6 +979,24 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
 	struct sdw_slave *slave;
 	int i, ret = 0;
 
+	/* first check if any Slaves fell off the bus */
+	for (i = 1; i <= SDW_MAX_DEVICES; i++) {
+		mutex_lock(&bus->bus_lock);
+		if (test_bit(i, bus->assigned) == false) {
+			mutex_unlock(&bus->bus_lock);
+			continue;
+		}
+		mutex_unlock(&bus->bus_lock);
+
+		slave = sdw_get_slave(bus, i);
+		if (!slave)
+			continue;
+
+		if (status[i] == SDW_SLAVE_UNATTACHED &&
+		    slave->status != SDW_SLAVE_UNATTACHED)
+			sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED);
+	}
+
 	if (status[0] == SDW_SLAVE_ATTACHED) {
 		dev_dbg(bus->dev, "Slave attached, programming device number\n");
 		ret = sdw_program_device_num(bus);