cpuidle: Do not use poll_idle unless user asks for it

[safe/jmp/linux-2.6] / drivers / cpuidle / governors / menu.c

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 78d77c5..b8f3e21 100644 (file)
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -34,21 +34,28 @@ static DEFINE_PER_CPU(struct menu_device, menu_devices);
 static int menu_select(struct cpuidle_device *dev)
 {
        struct menu_device *data = &__get_cpu_var(menu_devices);
+       int latency_req = pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY);
        int i;
 
+       /* Special case when user has set very strict latency requirement */
+       if (unlikely(latency_req == 0)) {
+               data->last_state_idx = 0;
+               return 0;
+       }
+
        /* determine the expected residency time */
        data->expected_us =
                (u32) ktime_to_ns(tick_nohz_get_sleep_length()) / 1000;
 
        /* find the deepest idle state that satisfies our constraints */
-       for (i = 1; i < dev->state_count; i++) {
+       for (i = CPUIDLE_DRIVER_STATE_START + 1; i < dev->state_count; i++) {
                struct cpuidle_state *s = &dev->states[i];
 
                if (s->target_residency > data->expected_us)
                        break;
                if (s->target_residency > data->predicted_us)
                        break;
-               if (s->exit_latency > pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY))
+               if (s->exit_latency > latency_req)
                        break;
        }