diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index ab755ea26c6a252587b936fe04b5f472b0354402..0fc90ba16ae1594d5ad7b9ba2dba771b954f1e05 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -137,7 +137,6 @@ static inline void check_wait(void)
 	case CPU_4KEC:
 	case CPU_4KSC:
 	case CPU_5KC:
-/*	case CPU_20KC:*/
 	case CPU_24K:
 	case CPU_25KF:
 	case CPU_34K:
@@ -156,6 +155,17 @@ static inline void check_wait(void)
 		if (allow_au1k_wait)
 			cpu_wait = au1k_wait;
 		break;
+	case CPU_20KC:
+		/*
+		 * WAIT on Rev1.0 has E1, E2, E3 and E16.
+		 * WAIT on Rev2.0 and Rev3.0 has E16.
+		 * Rev3.1 WAIT is nop, why bother
+		 */
+		if ((c->processor_id & 0xff) <= 0x64)
+			break;
+
+		cpu_wait = r4k_wait;
+		break;
 	case CPU_RM9000:
 		if ((c->processor_id & 0x00ff) >= 0x40)
 			cpu_wait = r4k_wait;