1 files changed, 82 insertions, 45 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index a55e68f2cfc..cb7019977c5 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -32,6 +32,7 @@ LIST_HEAD(cpuidle_detected_devices);
 static int enabled_devices;
 static int off __read_mostly;
 static int initialized __read_mostly;
+static bool use_deepest_state __read_mostly;
 
 int cpuidle_disabled(void)
 {
@@ -65,6 +66,45 @@ int cpuidle_play_dead(void)
 }
 
 /**
+ * cpuidle_use_deepest_state - Enable/disable the "deepest idle" mode.
+ * @enable: Whether enable or disable the feature.
+ *
+ * If the "deepest idle" mode is enabled, cpuidle will ignore the governor and
+ * always use the state with the greatest exit latency (out of the states that
+ * are not disabled).
+ *
+ * This function can only be called after cpuidle_pause() to avoid races.
+ */
+void cpuidle_use_deepest_state(bool enable)
+{
+	use_deepest_state = enable;
+}
+
+/**
+ * cpuidle_find_deepest_state - Find the state of the greatest exit latency.
+ * @drv: cpuidle driver for a given CPU.
+ * @dev: cpuidle device for a given CPU.
+ */
+static int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
+				      struct cpuidle_device *dev)
+{
+	unsigned int latency_req = 0;
+	int i, ret = CPUIDLE_DRIVER_STATE_START - 1;
+
+	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
+		struct cpuidle_state *s = &drv->states[i];
+		struct cpuidle_state_usage *su = &dev->states_usage[i];
+
+		if (s->disabled || su->disable || s->exit_latency <= latency_req)
+			continue;
+
+		latency_req = s->exit_latency;
+		ret = i;
+	}
+	return ret;
+}
+
+/**
  * cpuidle_enter_state - enter the state and update stats
  * @dev: cpuidle device for this cpu
  * @drv: cpuidle driver for this cpu
@@ -85,7 +125,8 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 
 	time_end = ktime_get();
 
-	local_irq_enable();
+	if (!cpuidle_state_is_coupled(dev, drv, entered_state))
+		local_irq_enable();
 
 	diff = ktime_to_us(ktime_sub(time_end, time_start));
 	if (diff > INT_MAX)
@@ -108,61 +149,57 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 }
 
 /**
- * cpuidle_idle_call - the main idle loop
+ * cpuidle_select - ask the cpuidle framework to choose an idle state
  *
- * NOTE: no locks or semaphores should be used here
- * return non-zero on failure
+ * @drv: the cpuidle driver
+ * @dev: the cpuidle device
+ *
+ * Returns the index of the idle state.
  */
-int cpuidle_idle_call(void)
+int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 {
-	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
-	struct cpuidle_driver *drv;
-	int next_state, entered_state;
-	bool broadcast;
-
 	if (off || !initialized)
 		return -ENODEV;
 
-	/* check if the device is ready */
-	if (!dev || !dev->enabled)
+	if (!drv || !dev || !dev->enabled)
 		return -EBUSY;
 
-	drv = cpuidle_get_cpu_driver(dev);
+	if (unlikely(use_deepest_state))
+		return cpuidle_find_deepest_state(drv, dev);
 
-	/* ask the governor for the next state */
-	next_state = cpuidle_curr_governor->select(drv, dev);
-	if (need_resched()) {
-		dev->last_residency = 0;
-		/* give the governor an opportunity to reflect on the outcome */
-		if (cpuidle_curr_governor->reflect)
-			cpuidle_curr_governor->reflect(dev, next_state);
-		local_irq_enable();
-		return 0;
-	}
-
-	trace_cpu_idle_rcuidle(next_state, dev->cpu);
-
-	broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP);
-
-	if (broadcast)
-		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
-
-	if (cpuidle_state_is_coupled(dev, drv, next_state))
-		entered_state = cpuidle_enter_state_coupled(dev, drv,
-							    next_state);
-	else
-		entered_state = cpuidle_enter_state(dev, drv, next_state);
-
-	if (broadcast)
-		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
-
-	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
+	return cpuidle_curr_governor->select(drv, dev);
+}
 
-	/* give the governor an opportunity to reflect on the outcome */
-	if (cpuidle_curr_governor->reflect)
-		cpuidle_curr_governor->reflect(dev, entered_state);
+/**
+ * cpuidle_enter - enter into the specified idle state
+ *
+ * @drv:   the cpuidle driver tied with the cpu
+ * @dev:   the cpuidle device
+ * @index: the index in the idle state table
+ *
+ * Returns the index in the idle state, < 0 in case of error.
+ * The error code depends on the backend driver
+ */
+int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
+		  int index)
+{
+	if (cpuidle_state_is_coupled(dev, drv, index))
+		return cpuidle_enter_state_coupled(dev, drv, index);
+	return cpuidle_enter_state(dev, drv, index);
+}
 
-	return 0;
+/**
+ * cpuidle_reflect - tell the underlying governor what was the state
+ * we were in
+ *
+ * @dev  : the cpuidle device
+ * @index: the index in the idle state table
+ *
+ */
+void cpuidle_reflect(struct cpuidle_device *dev, int index)
+{
+	if (cpuidle_curr_governor->reflect && !unlikely(use_deepest_state))
+		cpuidle_curr_governor->reflect(dev, index);
 }
 
 /**