diff --git a/include/linux/sched/walt.h b/include/linux/sched/walt.h
new file mode 100644
index 000000000000..f3fdd4da27e8
--- /dev/null
+++ b/include/linux/sched/walt.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2021, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef _LINUX_SCHED_WALT_H
+#define _LINUX_SCHED_WALT_H
+
+#include <linux/types.h>
+
+#if IS_ENABLED(CONFIG_SCHED_WALT)
+extern int sched_lpm_disallowed_time(int cpu, u64 *timeout);
+#else
+static inline int sched_lpm_disallowed_time(int cpu, u64 *timeout)
+{
+	return INT_MAX;
+}
+#endif
+
+#endif /* _LINUX_SCHED_WALT_H */
diff --git a/kernel/sched/walt/sched_avg.c b/kernel/sched/walt/sched_avg.c
index cec81ea98fba..ededab2476e6 100644
--- a/kernel/sched/walt/sched_avg.c
+++ b/kernel/sched/walt/sched_avg.c
@@ -237,14 +237,21 @@ unsigned int sched_get_cpu_util(int cpu)
 	return busy;
 }
 
-u64 sched_lpm_disallowed_time(int cpu)
+int sched_lpm_disallowed_time(int cpu, u64 *timeout)
 {
 	u64 now = sched_clock();
 	u64 bias_end_time = atomic64_read(&per_cpu(busy_hyst_end_time, cpu));
 
-	if (now < bias_end_time)
-		return bias_end_time - now;
+	if (unlikely(is_reserved(cpu))) {
+		*timeout = 10 * NSEC_PER_MSEC;
+		return 0; /* shallowest c-state */
+	}
 
-	return 0;
+	if (now < bias_end_time) {
+		*timeout = bias_end_time - now;
+		return 0; /* shallowest c-state */
+	}
+
+	return INT_MAX; /* don't care */
 }
 EXPORT_SYMBOL(sched_lpm_disallowed_time);
diff --git a/kernel/sched/walt/walt.h b/kernel/sched/walt/walt.h
index 50afd59cb54a..37c03d98182f 100644
--- a/kernel/sched/walt/walt.h
+++ b/kernel/sched/walt/walt.h
@@ -278,7 +278,6 @@ extern int sched_unpause_cpus(struct cpumask *unpause_cpus);
 
 extern unsigned int sched_get_cpu_util(int cpu);
 extern void sched_update_hyst_times(void);
-extern u64 sched_lpm_disallowed_time(int cpu);
 extern int
 sched_updown_migrate_handler(struct ctl_table *table, int write,
 			void __user *buffer, size_t *lenp, loff_t *ppos);