A null pointer dereference issue has been resolved in the Linux kernel. The issue occurs when `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`, causing a null pointer dereference in trace. To fix this, `typec port register altmode` is called to register DisplayPort alternate mode as a non-controllable mode when `CONFIG TYPEC DP ALTMODE` is not enabled.