Merge "surfaceflinger: fix fencing when composition mode switches"

1 files changed, 14 insertions, 5 deletions

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index d29d9c19e9..32f3e1835c 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1924,13 +1924,22 @@ void SurfaceFlinger::postFramebuffer()
         displayDevice->onSwapBuffersCompleted();
         displayDevice->makeCurrent(mEGLDisplay, mEGLContext);
         for (auto& layer : displayDevice->getVisibleLayersSortedByZ()) {
-            sp<Fence> releaseFence = Fence::NO_FENCE;
+            // The layer buffer from the previous frame (if any) is released
+            // by HWC only when the release fence from this frame (if any) is
+            // signaled.  Always get the release fence from HWC first.
+            auto hwcLayer = layer->getHwcLayer(hwcId);
+            sp<Fence> releaseFence = mHwc->getLayerReleaseFence(hwcId, hwcLayer);
+
+            // If the layer was client composited in the previous frame, we
+            // need to merge with the previous client target acquire fence.
+            // Since we do not track that, always merge with the current
+            // client target acquire fence when it is available, even though
+            // this is suboptimal.
             if (layer->getCompositionType(hwcId) == HWC2::Composition::Client) {
-                releaseFence = displayDevice->getClientTargetAcquireFence();
-            } else {
-                auto hwcLayer = layer->getHwcLayer(hwcId);
-                releaseFence = mHwc->getLayerReleaseFence(hwcId, hwcLayer);
+                releaseFence = Fence::merge("LayerRelease", releaseFence,
+                        displayDevice->getClientTargetAcquireFence());
             }
+
             layer->onLayerDisplayed(releaseFence);
         }
         if (hwcId >= 0) {