SurfaceFlinger: check fence when acquiring buffer with PTS
This is a fix for a condition where SurfaceFlinger may pass
a buffer to HWC before the fence was signaled. This can happen when
presentation timestamp is set and the buffer behind the front of
the queue has current timestamp.
Test: run a scenario that simulate the scenario
(PTS is always set to the past)
Bug: 123780024
Change-Id: Ib47bc5ebc50136c54b29bd301ad8d059f3dea947
diff --git a/services/surfaceflinger/BufferQueueLayer.cpp b/services/surfaceflinger/BufferQueueLayer.cpp
index edfeb0b..b39116a 100644
--- a/services/surfaceflinger/BufferQueueLayer.cpp
+++ b/services/surfaceflinger/BufferQueueLayer.cpp
@@ -235,9 +235,28 @@
const nsecs_t expectedPresentTime = mFlinger->mUseScheduler
? mFlinger->mScheduler->mPrimaryDispSync->expectedPresentTime()
: mFlinger->mPrimaryDispSync->expectedPresentTime();
+
+ // updateTexImage() below might drop the some buffers at the head of the queue if there is a
+ // buffer behind them which is timely to be presented. However this buffer may not be signaled
+ // yet. The code below makes sure that this wouldn't happen by setting maxFrameNumber to the
+ // last buffer that was signaled.
+ uint64_t lastSignaledFrameNumber = mLastFrameNumberReceived;
+ {
+ Mutex::Autolock lock(mQueueItemLock);
+ for (int i = 0; i < mQueueItems.size(); i++) {
+ bool fenceSignaled =
+ mQueueItems[i].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
+ if (!fenceSignaled) {
+ break;
+ }
+ lastSignaledFrameNumber = mQueueItems[i].mFrameNumber;
+ }
+ }
+ const uint64_t maxFrameNumberToAcquire =
+ std::min(mLastFrameNumberReceived.load(), lastSignaledFrameNumber);
status_t updateResult =
mConsumer->updateTexImage(&r, expectedPresentTime, &mAutoRefresh, &queuedBuffer,
- mLastFrameNumberReceived, releaseFence);
+ maxFrameNumberToAcquire, releaseFence);
if (updateResult == BufferQueue::PRESENT_LATER) {
// Producer doesn't want buffer to be displayed yet. Signal a
// layer update so we check again at the next opportunity.