1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 3f7e3cedd133..284d7af5a9c8 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -17,6 +17,30 @@
 static struct cpuidle_driver *cpuidle_curr_driver;
 DEFINE_SPINLOCK(cpuidle_driver_lock);
 
+static void __cpuidle_register_driver(struct cpuidle_driver *drv)
+{
+        int i;
+        /*
+         * cpuidle driver should set the drv->power_specified bit
+         * before registering if the driver provides
+         * power_usage numbers.
+         *
+         * If 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 (!drv->power_specified) {
+                for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++)
+                        drv->states[i].power_usage = -1 - i;
+        }
+}
+
+
 /**
  * cpuidle_register_driver - registers a driver
  * @drv: the driver
@@ -34,6 +58,7 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
                 spin_unlock(&cpuidle_driver_lock);
                 return -EBUSY;
         }
+        __cpuidle_register_driver(drv);
         cpuidle_curr_driver = drv;
         spin_unlock(&cpuidle_driver_lock);