2 files changed, 47 insertions, 7 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index dbefe15..a507108 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -74,6 +74,17 @@ static void cpuidle_idle_call(void)
 	 */
 	hrtimer_peek_ahead_timers();
 #endif
+
+	/*
+	 * Call the device's prepare function before calling the
+	 * governor's select function.  ->prepare gives the device's
+	 * cpuidle driver a chance to update any dynamic information
+	 * of its cpuidle states for the current idle period, e.g.
+	 * state availability, latencies, residencies, etc.
+	 */
+	if (dev->prepare)
+		dev->prepare(dev);
+
 	/* ask the governor for the next state */
 	next_state = cpuidle_curr_governor->select(dev);
 	if (need_resched()) {
@@ -282,6 +293,26 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
 
 	poll_idle_init(dev);
 
+	/*
+	 * cpuidle driver should set the dev->power_specified bit
+	 * before registering the device if the driver provides
+	 * power_usage numbers.
+	 *
+	 * For those devices whose ->power_specified is not set,
+	 * we fill in power_usage with decreasing values as the
+	 * cpuidle code has an implicit assumption that state Cn
+	 * uses less power than C(n-1).
+	 *
+	 * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
+	 * an power value of -1.  So we use -2, -3, etc, for other
+	 * c-states.
+	 */
+	if (!dev->power_specified) {
+		int i;
+		for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++)
+			dev->states[i].power_usage = -1 - i;
+	}
+
 	per_cpu(cpuidle_devices, dev->cpu) = dev;
 	list_add(&dev->device_list, &cpuidle_detected_devices);
 	if ((ret = cpuidle_add_sysfs(sys_dev))) {
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 1b128702..c2408bb 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -234,6 +234,7 @@ static int menu_select(struct cpuidle_device *dev)
 {
 	struct menu_device *data = &__get_cpu_var(menu_devices);
 	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
+	unsigned int power_usage = -1;
 	int i;
 	int multiplier;
 
@@ -278,19 +279,27 @@ static int menu_select(struct cpuidle_device *dev)
 	if (data->expected_us > 5)
 		data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
 
-
-	/* find the deepest idle state that satisfies our constraints */
+	/*
+	 * Find the idle state with the lowest power while satisfying
+	 * our constraints.
+	 */
 	for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++) {
 		struct cpuidle_state *s = &dev->states[i];
 
+		if (s->flags & CPUIDLE_FLAG_IGNORE)
+			continue;
 		if (s->target_residency > data->predicted_us)
-			break;
+			continue;
 		if (s->exit_latency > latency_req)
-			break;
+			continue;
 		if (s->exit_latency * multiplier > data->predicted_us)
-			break;
-		data->exit_us = s->exit_latency;
-		data->last_state_idx = i;
+			continue;
+
+		if (s->power_usage < power_usage) {
+			power_usage = s->power_usage;
+			data->last_state_idx = i;
+			data->exit_us = s->exit_latency;
+		}
 	}
 
 	return data->last_state_idx;