From 0a3c4d6f8c95a89875455e989278a440822968d7 Mon Sep 17 00:00:00 2001
From: Dan Stoza <stoza@google.com>
Date: Tue, 19 Apr 2016 11:56:20 -0700
Subject: [PATCH] DispSync: Don't resync if HW vsync is unavailable

Don't attempt to resync to hardware vsync if it's not available (if
the display is blanked), which should prevent unusual sequences of
commands (enable vsync, then unblank) to hardware composer.

Bug: 28177844
Change-Id: I9d6046fb0a346830e98829fd250642f0809d7e31
---
 services/surfaceflinger/SurfaceFlinger.cpp      | 5 +++--
 services/surfaceflinger/SurfaceFlinger_hwc1.cpp | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index c09920cd2e..a69b11b0c3 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -800,7 +800,8 @@ void SurfaceFlinger::resyncToHardwareVsync(bool makeAvailable) {
     if (makeAvailable) {
         mHWVsyncAvailable = true;
     } else if (!mHWVsyncAvailable) {
-        ALOGE("resyncToHardwareVsync called when HW vsync unavailable");
+        // Hardware vsync is not currently available, so abort the resync
+        // attempt for now
         return;
     }
 
@@ -834,7 +835,7 @@ void SurfaceFlinger::disableHardwareVsync(bool makeUnavailable) {
 void SurfaceFlinger::resyncWithRateLimit() {
     static constexpr nsecs_t kIgnoreDelay = ms2ns(500);
     if (systemTime() - mLastSwapTime > kIgnoreDelay) {
-        resyncToHardwareVsync(true);
+        resyncToHardwareVsync(false);
     }
 }
 
diff --git a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
index b0115988ef..00700ab590 100644
--- a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
+++ b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
@@ -820,7 +820,8 @@ void SurfaceFlinger::resyncToHardwareVsync(bool makeAvailable) {
     if (makeAvailable) {
         mHWVsyncAvailable = true;
     } else if (!mHWVsyncAvailable) {
-        ALOGE("resyncToHardwareVsync called when HW vsync unavailable");
+        // Hardware vsync is not currently available, so abort the resync
+        // attempt for now
         return;
     }
 
@@ -854,7 +855,7 @@ void SurfaceFlinger::disableHardwareVsync(bool makeUnavailable) {
 void SurfaceFlinger::resyncWithRateLimit() {
     static constexpr nsecs_t kIgnoreDelay = ms2ns(500);
     if (systemTime() - mLastSwapTime > kIgnoreDelay) {
-        resyncToHardwareVsync(true);
+        resyncToHardwareVsync(false);
     }
 }
 
-- 
2.11.0