cpuidle: extend cpuidle and menu governor to handle dynamic states

[sfrench/cifs-2.6.git] / drivers / cpuidle / cpuidle.c

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index dbefe15bd582804497cbca76b6f3ce4fae6e28da..a507108433785f8432b3d15504c3a036b461c1a0 100644 (file)
--- 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))) {