1 files changed, 17 insertions, 1 deletions
diff --git a/libs/gui/DisplayEventDispatcher.cpp b/libs/gui/DisplayEventDispatcher.cpp
index c986b82fd8..837967551d 100644
--- a/libs/gui/DisplayEventDispatcher.cpp
+++ b/libs/gui/DisplayEventDispatcher.cpp
@@ -33,10 +33,13 @@ namespace android {
 // using just a few large reads.
 static const size_t EVENT_BUFFER_SIZE = 100;
 
+static constexpr nsecs_t WAITING_FOR_VSYNC_TIMEOUT = ms2ns(300);
+
 DisplayEventDispatcher::DisplayEventDispatcher(
         const sp<Looper>& looper, ISurfaceComposer::VsyncSource vsyncSource,
         ISurfaceComposer::EventRegistrationFlags eventRegistration)
-      : mLooper(looper), mReceiver(vsyncSource, eventRegistration), mWaitingForVsync(false) {
+      : mLooper(looper), mReceiver(vsyncSource, eventRegistration), mWaitingForVsync(false),
+        mLastVsyncCount(0), mLastScheduleVsyncTime(0) {
     ALOGV("dispatcher %p ~ Initializing display event dispatcher.", this);
 }
 
@@ -86,6 +89,7 @@ status_t DisplayEventDispatcher::scheduleVsync() {
         }
 
         mWaitingForVsync = true;
+        mLastScheduleVsyncTime = systemTime(SYSTEM_TIME_MONOTONIC);
     }
     return OK;
 }
@@ -124,9 +128,21 @@ int DisplayEventDispatcher::handleEvent(int, int events, void*) {
               this, ns2ms(vsyncTimestamp), to_string(vsyncDisplayId).c_str(), vsyncCount,
               vsyncEventData.id);
         mWaitingForVsync = false;
+        mLastVsyncCount = vsyncCount;
         dispatchVsync(vsyncTimestamp, vsyncDisplayId, vsyncCount, vsyncEventData);
     }
 
+    if (mWaitingForVsync) {
+        const nsecs_t currentTime = systemTime(SYSTEM_TIME_MONOTONIC);
+        const nsecs_t vsyncScheduleDelay = currentTime - mLastScheduleVsyncTime;
+        if (vsyncScheduleDelay > WAITING_FOR_VSYNC_TIMEOUT) {
+            ALOGW("Vsync time out! vsyncScheduleDelay=%" PRId64 "ms", ns2ms(vsyncScheduleDelay));
+            mWaitingForVsync = false;
+            dispatchVsync(currentTime, vsyncDisplayId /* displayId is not used */,
+                          ++mLastVsyncCount, vsyncEventData /* empty data */);
+        }
+    }
+
     return 1; // keep the callback
 }