Hi Dan, thank you for the reference. In this case I think returning NULL from ucsi_register_displayport stub and using a NULL check to prevent a NULL pointer dereference won't give us the desired behavior. When CONFIG_TYPEC_DP_ALTMODE is not enabled, the function would return NULL and the UCSI driver will never end up registering DisplayPort alternate mode. I'll update the commit message to note that this patch adds a fallback registration for DisplayPort alternate mode in addition to simply fixing the NULL pointer dereference caused by returning it in the ucsi_register_displayport stub. Separately we could add a NULL check, but I don't think it's necessary. Neither the non-stub ucsi_register_displayport or typec_port_register_altmode look like they will return NULL. Thanks, Jameson
