2 files changed, 12 insertions, 2 deletions

diff --git a/Documentation/cpuidle/sysfs.txt b/Documentation/cpuidle/sysfs.txt
index 9d28a3406e74..b6f44f490ed7 100644
--- a/Documentation/cpuidle/sysfs.txt
+++ b/Documentation/cpuidle/sysfs.txt
@@ -76,9 +76,17 @@ total 0
 
 
 * desc : Small description about the idle state (string)
-* disable : Option to disable this idle state (bool)
+* disable : Option to disable this idle state (bool) -> see note below
 * latency : Latency to exit out of this idle state (in microseconds)
 * name : Name of the idle state (string)
 * power : Power consumed while in this idle state (in milliwatts)
 * time : Total time spent in this idle state (in microseconds)
 * usage : Number of times this state was entered (count)
+
+Note:
+The behavior and the effect of the disable variable depends on the
+implementation of a particular governor. In the ladder governor, for
+example, it is not coherent, i.e. if one is disabling a light state,
+then all deeper states are disabled as well, but the disable variable
+does not reflect it. Likewise, if one enables a deep state but a lighter
+state still is disabled, then this has no effect.
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index b6a09ea859b1..2aef26c520bb 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -88,6 +88,7 @@ static int ladder_select_state(struct cpuidle_driver *drv,
 
         /* consider promotion */
         if (last_idx < drv->state_count - 1 &&
+            !dev->states_usage[last_idx + 1].disable &&
             last_residency > last_state->threshold.promotion_time &&
             drv->states[last_idx + 1].exit_latency <= latency_req) {
                 last_state->stats.promotion_count++;
@@ -100,7 +101,8 @@ static int ladder_select_state(struct cpuidle_driver *drv,
 
         /* consider demotion */
         if (last_idx > CPUIDLE_DRIVER_STATE_START &&
-            drv->states[last_idx].exit_latency > latency_req) {
+            (dev->states_usage[last_idx].disable ||
+            drv->states[last_idx].exit_latency > latency_req)) {
                 int i;
 
                 for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) {