Backlight off should not transition to dim or off states

backlight_controller.cc

Index: backlight_controller.cc
diff --git a/backlight_controller.cc b/backlight_controller.cc
index fa1507440478601b134bb5e8bb389edb176f3a84..3740cf2b769f3f0f4d36f6824bdef2d7aad94e2b 100644
--- a/backlight_controller.cc
+++ b/backlight_controller.cc
@@ -128,12 +128,17 @@ void BacklightController::DecreaseBrightness() {
   }
 }
 
-
 bool BacklightController::SetPowerState(PowerState state) {
   if (state == state_ || !is_initialized_)
     return false;
   CHECK(state != BACKLIGHT_UNINITIALIZED);
 
+  // If backlight is turned off, do not transition to dim or off states.
+  // From ACTIVE_OFF state only transition to ACTIVE_ON and SUSPEND states.
+  if (state_ == BACKLIGHT_ACTIVE_OFF && (state == BACKLIGHT_IDLE_OFF ||
+                                         state == BACKLIGHT_DIM))
+    return false;
+
   LOG(INFO) << PowerStateToString(state_) << " -> "
             << PowerStateToString(state);
   ReadBrightness();