diff --git a/kernel/power/main.c b/kernel/power/main.c
index 6ee2cad..d253f3a 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -24,7 +24,7 @@
 
 DECLARE_MUTEX(pm_sem);
 
-struct pm_ops * pm_ops = NULL;
+struct pm_ops *pm_ops;
 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
 
 /**
@@ -151,6 +151,18 @@
 #endif
 };
 
+static inline int valid_state(suspend_state_t state)
+{
+	/* Suspend-to-disk does not really need low-level support.
+	 * It can work with reboot if needed. */
+	if (state == PM_SUSPEND_DISK)
+		return 1;
+
+	if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
+		return 0;
+	return 1;
+}
+
 
 /**
  *	enter_state - Do common work of entering low-power state.
@@ -167,7 +179,7 @@
 {
 	int error;
 
-	if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
+	if (!valid_state(state))
 		return -ENODEV;
 	if (down_trylock(&pm_sem))
 		return -EBUSY;
@@ -238,9 +250,8 @@
 	char * s = buf;
 
 	for (i = 0; i < PM_SUSPEND_MAX; i++) {
-		if (pm_states[i] && pm_ops && (!pm_ops->valid
-			||(pm_ops->valid && pm_ops->valid(i))))
-			s += sprintf(s,"%s ",pm_states[i]);
+		if (pm_states[i] && valid_state(i))
+			s += sprintf(s,"%s ", pm_states[i]);
 	}
 	s += sprintf(s,"\n");
 	return (s - buf);