cpuidle: Allow enforcing deepest idle state selection

When idle injection is used to cap power, we need to override the
governor's choice of idle states.

For this reason, make it possible the deepest idle state selection to
be enforced by setting a flag on a given CPU to achieve the maximum
potential power draw reduction.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
[ rjw: Subject & changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 1d8718d5300d..513e4dfeeae7 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -164,11 +164,14 @@ static void cpuidle_idle_call(void)
          * timekeeping to prevent timer interrupts from kicking us out of idle
          * until a proper wakeup interrupt happens.
          */
-        if (idle_should_freeze()) {
-                entered_state = cpuidle_enter_freeze(drv, dev);
-                if (entered_state > 0) {
-                        local_irq_enable();
-                        goto exit_idle;
+
+        if (idle_should_freeze() || dev->use_deepest_state) {
+                if (idle_should_freeze()) {
+                        entered_state = cpuidle_enter_freeze(drv, dev);
+                        if (entered_state > 0) {
+                                local_irq_enable();
+                                goto exit_idle;
+                        }
                 }
 
                 next_state = cpuidle_find_deepest_state(drv, dev);