--- /dev/null
+--- a/arch/mips/ath79/prom.c
++++ b/arch/mips/ath79/prom.c
+@@ -136,6 +136,13 @@ void __init prom_init(void)
+ initrd_end = initrd_start + fw_getenvl("initrd_size");
+ }
+ #endif
++
++ if (strstr(arcs_cmdline, "board=750Gr3") ||
++ strstr(arcs_cmdline, "board=951G") ||
++ strstr(arcs_cmdline, "board=2011L") ||
++ strstr(arcs_cmdline, "board=711Gr100") ||
++ strstr(arcs_cmdline, "board=922gs"))
++ ath79_prom_append_cmdline("console", "ttyS0,115200");
+ }
+
+ void __init prom_free_prom_memory(void)