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path: root/drivers/cpuidle/driver.c
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Diffstat (limited to 'drivers/cpuidle/driver.c')
-rw-r--r--drivers/cpuidle/driver.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 3f7e3cedd13..284d7af5a9c 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);