usb: typec: tcpm: Handle vbus shutoff when in source mode

While in source mode, vbus could be shutoff by protections
circuits. TCPM does not move back to toggling state to
re-initiate connection. Fix this by moving to SRC_UNATTACHED
state when vbus shuts off while in source mode.
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20210201100212.49863-1-badhri@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpm.c

@@ -4897,6 +4897,17 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
 		/* Do nothing, waiting for sink detection */
 		break;
 
+	case SRC_STARTUP:
+	case SRC_SEND_CAPABILITIES:
+	case SRC_SEND_CAPABILITIES_TIMEOUT:
+	case SRC_NEGOTIATE_CAPABILITIES:
+	case SRC_TRANSITION_SUPPLY:
+	case SRC_READY:
+	case SRC_WAIT_NEW_CAPABILITIES:
+		/* Force to unattached state to re-initiate connection */
+		tcpm_set_state(port, SRC_UNATTACHED, 0);
+		break;
+
 	case PORT_RESET:
 		/*
 		 * State set back to default mode once the timer completes.