usb: typec: ucsi: Fix null pointer dereference in trace

ucsi_register_altmode checks IS_ERR for the alt pointer and treats
NULL as valid. When CONFIG_TYPEC_DP_ALTMODE is not enabled,
ucsi_register_displayport returns NULL which causes a NULL pointer
dereference in trace. Rather than return NULL, call
typec_port_register_altmode to register DisplayPort alternate mode
as a non-controllable mode when CONFIG_TYPEC_DP_ALTMODE is not enabled.

Reviewed-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Jameson Thies <jthies@google.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240510201244.2968152-2-jthies@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
index e70cf5b15562e00c8743bd89bab5d69968b1d798..8b4cd0c879a8a9a1e3ff68ef0cb00641b4223eae 100644 (file)
--- a/drivers/usb/typec/ucsi/ucsi.h
+++ b/drivers/usb/typec/ucsi/ucsi.h
@@ -501,7 +501,7 @@ ucsi_register_displayport(struct ucsi_connector *con,
                          bool override, int offset,
                          struct typec_altmode_desc *desc)
 {
-       return NULL;
+       return typec_port_register_altmode(con->port, desc);
 }
 
 static inline void