usb: typec: tcpm: Add WARN_ON ensure we are not trying to send 2 VDM packets at the same time

The tcpm.c code for sending VDMs assumes that there will only be one VDM
in flight at the time. The "queue" used by tcpm_queue_vdm is only 1 entry
deep.

This assumes that the higher layers (tcpm state-machine and alt-mode
drivers) ensure that queuing a new VDM before the old one has been
completely send (or it timed out) add a WARN_ON to check for this.
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20200724174702.61754-6-hdegoede@redhat.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpm.c

@@ -971,6 +971,9 @@ static void tcpm_queue_vdm(struct tcpm_port *port, const u32 header,
 {
 	WARN_ON(!mutex_is_locked(&port->lock));
 
+	/* Make sure we are not still processing a previous VDM packet */
+	WARN_ON(port->vdm_state > VDM_STATE_DONE);
+
 	port->vdo_count = cnt + 1;
 	port->vdo_data[0] = header;
 	memcpy(&port->vdo_data[1], data, sizeof(u32) * cnt);