From afb6b50ee815108a6f5f290e1b3753069f3bd9d3 Mon Sep 17 00:00:00 2001
From: Rachel Lee <rnlee@google.com>
Date: Fri, 12 May 2023 15:53:05 -0700
Subject: Populate preferred frame timeline always

`getLatestVsyncEventData` sometimes ends up with 0 length frame
timelines. When `generateFrameTimeline`, always populate with the
preferred timeline information from the vsync schedule.

Bug: 282110947
Test: atest EventThreadTest
Test: atest DisplayEventReceiverTest
Change-Id: I936d3b7095ce89ce3bd898f6b6a4f73145c27160
---
 services/surfaceflinger/Scheduler/EventThread.cpp | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/services/surfaceflinger/Scheduler/EventThread.cpp b/services/surfaceflinger/Scheduler/EventThread.cpp
index af9acf3346..281b0ae559 100644
--- a/services/surfaceflinger/Scheduler/EventThread.cpp
+++ b/services/surfaceflinger/Scheduler/EventThread.cpp
@@ -612,6 +612,15 @@ void EventThread::generateFrameTimeline(VsyncEventData& outVsyncEventData, nsecs
                 preferredExpectedPresentationTime + multiplier * frameInterval;
         if (expectedPresentationTime >= preferredExpectedPresentationTime +
                     scheduler::VsyncConfig::kEarlyLatchMaxThreshold.count()) {
+            if (currentIndex == 0) {
+                ALOGW("%s: Expected present time is too far in the future but no timelines are "
+                      "valid. preferred EPT=%" PRId64 ", Calculated EPT=%" PRId64
+                      ", multiplier=%" PRId64 ", frameInterval=%" PRId64 ", threshold=%" PRId64,
+                      __func__, preferredExpectedPresentationTime, expectedPresentationTime,
+                      multiplier, frameInterval,
+                      static_cast<int64_t>(
+                              scheduler::VsyncConfig::kEarlyLatchMaxThreshold.count()));
+            }
             break;
         }
 
@@ -625,6 +634,20 @@ void EventThread::generateFrameTimeline(VsyncEventData& outVsyncEventData, nsecs
                  .expectedPresentationTime = expectedPresentationTime};
         currentIndex++;
     }
+
+    if (currentIndex == 0) {
+        ALOGW("%s: No timelines are valid. preferred EPT=%" PRId64 ", frameInterval=%" PRId64
+              ", threshold=%" PRId64,
+              __func__, preferredExpectedPresentationTime, frameInterval,
+              static_cast<int64_t>(scheduler::VsyncConfig::kEarlyLatchMaxThreshold.count()));
+        outVsyncEventData.frameTimelines[currentIndex] =
+                {.vsyncId = generateToken(timestamp, preferredDeadlineTimestamp,
+                                          preferredExpectedPresentationTime),
+                 .deadlineTimestamp = preferredDeadlineTimestamp,
+                 .expectedPresentationTime = preferredExpectedPresentationTime};
+        currentIndex++;
+    }
+
     outVsyncEventData.frameTimelinesLength = currentIndex;
 }
 
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