usb: typec: ucsi: register DP only for NVIDIA DP VDO

NVIDIA VirtualLink (svid 0x955) has two altmode, vdo=0x1 for
VirtualLink DP mode and vdo=0x3 for NVIDIA test mode.
Register display altmode driver only for vdo=0x1
Signed-off-by: Ajay Gupta <ajayg@nvidia.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20200217144913.55330-2-heikki.krogerus@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/ucsi/ucsi.c

@@ -270,9 +270,16 @@ static int ucsi_register_altmode(struct ucsi_connector *con,
 
 		switch (desc->svid) {
 		case USB_TYPEC_DP_SID:
-		case USB_TYPEC_NVIDIA_VLINK_SID:
 			alt = ucsi_register_displayport(con, override, i, desc);
 			break;
+		case USB_TYPEC_NVIDIA_VLINK_SID:
+			if (desc->vdo == USB_TYPEC_NVIDIA_VLINK_DBG_VDO)
+				alt = typec_port_register_altmode(con->port,
+								  desc);
+			else
+				alt = ucsi_register_displayport(con, override,
+								i, desc);
+			break;
 		default:
 			alt = typec_port_register_altmode(con->port, desc);
 			break;
@@ -475,7 +482,8 @@ static void ucsi_unregister_altmodes(struct ucsi_connector *con, u8 recipient)
 	while (adev[i]) {
 		if (recipient == UCSI_RECIPIENT_SOP &&
 		    (adev[i]->svid == USB_TYPEC_DP_SID ||
-			adev[i]->svid == USB_TYPEC_NVIDIA_VLINK_SID)) {
+			(adev[i]->svid == USB_TYPEC_NVIDIA_VLINK_SID &&
+			adev[i]->vdo != USB_TYPEC_NVIDIA_VLINK_DBG_VDO))) {
 			pdev = typec_altmode_get_partner(adev[i]);
 			ucsi_displayport_remove_partner((void *)pdev);
 		}

drivers/usb/typec/ucsi/ucsi.h

@@ -340,4 +340,11 @@ static inline void
 ucsi_displayport_remove_partner(struct typec_altmode *adev) { }
 #endif /* CONFIG_TYPEC_DP_ALTMODE */
 
+/*
+ * NVIDIA VirtualLink (svid 0x955) has two altmode. VirtualLink
+ * DP mode with vdo=0x1 and NVIDIA test mode with vdo=0x3
+ */
+#define USB_TYPEC_NVIDIA_VLINK_DP_VDO	0x1
+#define USB_TYPEC_NVIDIA_VLINK_DBG_VDO	0x3
+
 #endif /* __DRIVER_USB_TYPEC_UCSI_H */