[PATCH 6/6] usb: typec: ucsi: pr_swap should check connector_status

[Jameson Thies <jthies@google.com>]

From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>

Power role swaps initiated by the host system doesn't generate
connection status change notifications.

From UCSIv3.0 spec, section 6.5.10 Set Power Direction Role:

The execution of this command might require PPM to initiate a power
role swap. If the power role swap fails for any reason, the command
returns, and error and the power direction should remain unchanged.
Note that if the execution of the command resulted in a successful
power role swap, it should not result in a connector status change
notification.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Jameson Thies <jthies@google.com>
---
 drivers/usb/typec/ucsi/ucsi.c | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 1a7d850b11ea..6e3797d7a144 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -1526,20 +1526,40 @@ static int ucsi_pr_swap(struct typec_port *port, enum typec_role role)
 	if (ret < 0)
 		goto out_unlock;
 
-	mutex_unlock(&con->lock);
+	command = UCSI_GET_CONNECTOR_STATUS | UCSI_CONNECTOR_NUMBER(con->num);
+	ret = ucsi_send_command(con->ucsi, command, &con->status, sizeof(con->status));
+	if (ret < 0)
+		goto out_unlock;
 
-	if (!wait_for_completion_timeout(&con->complete,
-					 msecs_to_jiffies(UCSI_SWAP_TIMEOUT_MS)))
-		return -ETIMEDOUT;
+	cur_role = !!UCSI_CONSTAT(con, PWR_DIR);
 
-	mutex_lock(&con->lock);
+	/* Execution of SET_PDR should not result in connector status
+	 * notifications. However, some legacy implementations may still defer
+	 * the actual role swap and return immediately. Thus, check the
+	 * connector status in case it immediately succeeded or wait for a later
+	 * connector status change.
+	 */
+	if (cur_role != role) {
+		mutex_unlock(&con->lock);
+
+		if (!wait_for_completion_timeout(
+			    &con->complete,
+			    msecs_to_jiffies(UCSI_SWAP_TIMEOUT_MS)))
+			return -ETIMEDOUT;
+
+		mutex_lock(&con->lock);
+	}
 
 	/* Something has gone wrong while swapping the role */
 	if (UCSI_CONSTAT(con, PWR_OPMODE) != UCSI_CONSTAT_PWR_OPMODE_PD) {
 		ucsi_reset_connector(con, true);
 		ret = -EPROTO;
+		goto out_unlock;
 	}
 
+	/* Indicate successful power role swap */
+	typec_set_pwr_role(con->port, role);
+
 out_unlock:
 	mutex_unlock(&con->lock);
 
-- 
2.51.0.618.g983fd99d29-goog