set system screen never sleep

diff --git a/frameworks/base/services/core/java/com/android/server/power/PowerMa
index e76b458..6bbea52 100644
--- a/frameworks/base/services/core/java/com/android/server/power/PowerManagerSe
+++ b/frameworks/base/services/core/java/com/android/server/power/PowerManagerSe
@@ -1739,6 +1739,10 @@ public final class PowerManagerService extends SystemServ

     private int getScreenOffTimeoutLocked(int sleepTimeout) {
         int timeout = mScreenOffTimeoutSetting;
+        if(timeout < 0)
+        {
+            return mMaximumScreenOffTimeoutFromDeviceAdmin;
+        }
         if (isMaximumScreenOffTimeoutFromDeviceAdminEnforcedLocked()) {
             timeout = Math.min(timeout, mMaximumScreenOffTimeoutFromDeviceAdmin
         }