soundwire: bus: fix io error when processing alert event

There are two types of io errors when processing alert event.

a) the Master detects an ALERT status for e.g. a jack event and
invokes the implementation-defined function in the Slave driver to
check the jack status. At this time the codec is just suspended, so io
registers can't be accessed.

b) when waking up from clock stop mode1 state, where the bus needs a
complete re-enumeration, Slave registers can't be accessed until the
enumeration is complete.

This patch resumes the Slave device and waits for initialization
complete when processing slave alert event, so that registers on the
Slave can be accessed without timeouts or io errors.
Signed-off-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200115000844.14695-9-pierre-louis.bossart@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/bus.c

@@ -890,12 +890,19 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 
 	sdw_modify_slave_status(slave, SDW_SLAVE_ALERT);
 
+	ret = pm_runtime_get_sync(&slave->dev);
+	if (ret < 0 && ret != -EACCES) {
+		dev_err(&slave->dev, "Failed to resume device: %d\n", ret);
+		pm_runtime_put_noidle(slave->bus->dev);
+		return ret;
+	}
+
 	/* Read Instat 1, Instat 2 and Instat 3 registers */
 	ret = sdw_read(slave, SDW_SCP_INT1);
 	if (ret < 0) {
 		dev_err(slave->bus->dev,
 			"SDW_SCP_INT1 read failed:%d\n", ret);
-		return ret;
+		goto io_err;
 	}
 	buf = ret;
 
@@ -903,7 +910,7 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 	if (ret < 0) {
 		dev_err(slave->bus->dev,
 			"SDW_SCP_INT2/3 read failed:%d\n", ret);
-		return ret;
+		goto io_err;
 	}
 
 	do {
@@ -983,7 +990,7 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 		if (ret < 0) {
 			dev_err(slave->bus->dev,
 				"SDW_SCP_INT1 write failed:%d\n", ret);
-			return ret;
+			goto io_err;
 		}
 
 		/*
@@ -994,7 +1001,7 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 		if (ret < 0) {
 			dev_err(slave->bus->dev,
 				"SDW_SCP_INT1 read failed:%d\n", ret);
-			return ret;
+			goto io_err;
 		}
 		_buf = ret;
 
@@ -1002,7 +1009,7 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 		if (ret < 0) {
 			dev_err(slave->bus->dev,
 				"SDW_SCP_INT2/3 read failed:%d\n", ret);
-			return ret;
+			goto io_err;
 		}
 
 		/* Make sure no interrupts are pending */
@@ -1023,6 +1030,10 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 	if (count == SDW_READ_INTR_CLEAR_RETRY)
 		dev_warn(slave->bus->dev, "Reached MAX_RETRY on alert read\n");
 
+io_err:
+	pm_runtime_mark_last_busy(&slave->dev);
+	pm_runtime_put_autosuspend(&slave->dev);
+
 	return ret;
 }