From 0eb2d398669bf11207c0fb22b11439250da0c8dc Mon Sep 17 00:00:00 2001
From: Dan Stoza <stoza@google.com>
Date: Mon, 6 Jul 2015 12:56:50 -0700
Subject: [PATCH] SF: Ignore PTS more than one second in the future

Some of this logic already existed, but when we optimized
SurfaceFlinger to avoid unnecessary wake-ups, we didn't carry the logic
over into the new readiness test. shouldPresentNow now returns true if
the timestamp is more than a second in the future (since it's likely a
bogus timestamp and should be ignored).

Bug: 21932760
Change-Id: Ib50970a4eb621588c0b60766c8d8d1a8bddf853b
---
 services/surfaceflinger/Layer.cpp | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 91f80b60e..e2418cc37 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -1102,10 +1102,21 @@ void Layer::useEmptyDamage() {
 
 bool Layer::shouldPresentNow(const DispSync& dispSync) const {
     Mutex::Autolock lock(mQueueItemLock);
+    if (mQueueItems.empty()) {
+        return false;
+    }
+    auto timestamp = mQueueItems[0].mTimestamp;
     nsecs_t expectedPresent =
             mSurfaceFlingerConsumer->computeExpectedPresent(dispSync);
-    return mQueueItems.empty() ?
-            false : mQueueItems[0].mTimestamp < expectedPresent;
+
+    // Ignore timestamps more than a second in the future
+    bool isPlausible = timestamp < (expectedPresent + s2ns(1));
+    ALOGW_IF(!isPlausible, "[%s] Timestamp %" PRId64 " seems implausible "
+            "relative to expectedPresent %" PRId64, mName.string(), timestamp,
+            expectedPresent);
+
+    bool isDue = timestamp < expectedPresent;
+    return isDue || !isPlausible;
 }
 
 bool Layer::onPreComposition() {