diff --git a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c
index 87703df..cbca1df 100644
--- a/arch/powerpc/kernel/udbg.c
+++ b/arch/powerpc/kernel/udbg.c
@@ -151,12 +151,18 @@
 
 static int early_console_initialized;
 
-/* called by setup_system */
+/*
+ * Called by setup_system after ppc_md->probe and ppc_md->early_init.
+ * Call it again after setting udbg_putc in ppc_md->setup_arch.
+ */
 void register_early_udbg_console(void)
 {
 	if (early_console_initialized)
 		return;
 
+	if (!udbg_putc)
+		return;
+
 	if (strstr(boot_command_line, "udbg-immortal")) {
 		printk(KERN_INFO "early console immortal !\n");
 		udbg_console.flags &= ~CON_BOOT;