7 files changed, 28 insertions, 22 deletions

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index 8c7930b5a65f..7e48eb5bf0a7 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -19,11 +19,9 @@ config CPU_IDLE_MULTIPLE_DRIVERS
 
 config CPU_IDLE_GOV_LADDER
         bool "Ladder governor (for periodic timer tick)"
-        default y
 
 config CPU_IDLE_GOV_MENU
         bool "Menu governor (for tickless system)"
-        default y
 
 config DT_IDLE_STATES
         bool
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 17a6dc0e2111..046423b0c5ca 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -79,9 +79,9 @@ static int find_deepest_state(struct cpuidle_driver *drv,
                               bool freeze)
 {
         unsigned int latency_req = 0;
-        int i, ret = -ENXIO;
+        int i, ret = 0;
 
-        for (i = 0; i < drv->state_count; i++) {
+        for (i = 1; i < drv->state_count; i++) {
                 struct cpuidle_state *s = &drv->states[i];
                 struct cpuidle_state_usage *su = &dev->states_usage[i];
 
@@ -243,7 +243,7 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
  * @drv: the cpuidle driver
  * @dev: the cpuidle device
  *
- * Returns the index of the idle state.
+ * Returns the index of the idle state.  The return value must not be negative.
  */
 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 {
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index 401c0106ed34..63bd5a403e22 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -17,6 +17,7 @@
 #include <linux/pm_qos.h>
 #include <linux/module.h>
 #include <linux/jiffies.h>
+#include <linux/tick.h>
 
 #include <asm/io.h>
 #include <asm/uaccess.h>
@@ -184,6 +185,14 @@ static struct cpuidle_governor ladder_governor = {
  */
 static int __init init_ladder(void)
 {
+        /*
+         * When NO_HZ is disabled, or when booting with nohz=off, the ladder
+         * governor is better so give it a higher rating than the menu
+         * governor.
+         */
+        if (!tick_nohz_enabled)
+                ladder_governor.rating = 25;
+
         return cpuidle_register_governor(&ladder_governor);
 }
 
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 7b0971d97cc3..0742b3296673 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -294,8 +294,6 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
                 data->needs_update = 0;
         }
 
-        data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1;
-
         /* Special case when user has set very strict latency requirement */
         if (unlikely(latency_req == 0))
                 return 0;
@@ -326,20 +324,25 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
         if (latency_req > interactivity_req)
                 latency_req = interactivity_req;
 
-        /*
-         * We want to default to C1 (hlt), not to busy polling
-         * unless the timer is happening really really soon.
-         */
-        if (interactivity_req > 20 &&
-            !drv->states[CPUIDLE_DRIVER_STATE_START].disabled &&
-                dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable == 0)
+        if (CPUIDLE_DRIVER_STATE_START > 0) {
+                data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1;
+                /*
+                 * We want to default to C1 (hlt), not to busy polling
+                 * unless the timer is happening really really soon.
+                 */
+                if (interactivity_req > 20 &&
+                    !drv->states[CPUIDLE_DRIVER_STATE_START].disabled &&
+                        dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable == 0)
+                        data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
+        } else {
                 data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
+        }
 
         /*
          * Find the idle state with the lowest power while satisfying
          * our constraints.
          */
-        for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
+        for (i = data->last_state_idx + 1; i < drv->state_count; i++) {
                 struct cpuidle_state *s = &drv->states[i];
                 struct cpuidle_state_usage *su = &dev->states_usage[i];
 
diff --git a/include/linux/tick.h b/include/linux/tick.h
index e312219ff823..97fd4e543846 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -98,6 +98,7 @@ static inline void tick_broadcast_exit(void)
 }
 
 #ifdef CONFIG_NO_HZ_COMMON
+extern int tick_nohz_enabled;
 extern int tick_nohz_tick_stopped(void);
 extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);
@@ -106,6 +107,7 @@ extern ktime_t tick_nohz_get_sleep_length(void);
 extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
 extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
 #else /* !CONFIG_NO_HZ_COMMON */
+#define tick_nohz_enabled (0)
 static inline int tick_nohz_tick_stopped(void) { return 0; }
 static inline void tick_nohz_idle_enter(void) { }
 static inline void tick_nohz_idle_exit(void) { }
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 4a2ef5a02fd3..34852ee70d54 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -97,12 +97,6 @@ void default_idle_call(void)
 static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
                       int next_state)
 {
-        /* Fall back to the default arch idle method on errors. */
-        if (next_state < 0) {
-                default_idle_call();
-                return next_state;
-        }
-
         /*
          * The idle task must be scheduled, it is pointless to go to idle, just
          * update no idle residency and return.
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 9cc20af58c76..9d7a053545f5 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -387,7 +387,7 @@ void __init tick_nohz_init(void)
 /*
  * NO HZ enabled ?
  */
-static int tick_nohz_enabled __read_mostly  = 1;
+int tick_nohz_enabled __read_mostly = 1;
 unsigned long tick_nohz_active  __read_mostly;
 /*
  * Enable / Disable tickless mode