commit faf77cce9d9ec0238d6999b3bd0d40c71ff403c5
author Jamie Gennis <jgennis@google.com> Tue Jul 30 15:10:32 2013 -0700
committer Jamie Gennis <jgennis@google.com> Mon Oct 07 17:59:53 2013 -0700
tree 82eb0a16649cbe4abf4dc4b2036348df6e3d99df
parent d457ec52d7023e9a6112f313cd2bf94293162214

SurfaceFlinger: SW-based vsync events

This change adds the DispSync class, which models the hardware vsync event
times to allow vsync event callbacks to be done at an arbitrary phase offset
from the hardware vsync.  This can be used to reduce the minimum latency from
Choreographer wake-up to on-screen image presentation.

Bug: 10624956
Change-Id: I8c7a54ceacaa4d709726ed97b0dcae4093a7bdcf

services/surfaceflinger/EventThread.cpp

diff --git a/services/surfaceflinger/EventThread.cpp b/services/surfaceflinger/EventThread.cpp
index a61ad72..3528b62 100644
--- a/services/surfaceflinger/EventThread.cpp
+++ b/services/surfaceflinger/EventThread.cpp
@@ -36,9 +36,10 @@
 namespace android {
 // ---------------------------------------------------------------------------
 
-EventThread::EventThread(const sp<SurfaceFlinger>& flinger)
-    : mFlinger(flinger),
+EventThread::EventThread(const sp<VSyncSource>& src)
+    : mVSyncSource(src),
       mUseSoftwareVSync(false),
+      mVsyncEnabled(false),
       mDebugVsyncEnabled(false) {
 
     for (int32_t i=0 ; i<DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES ; i++) {
@@ -110,19 +111,13 @@
     }
 }
 
-
-void EventThread::onVSyncReceived(int type, nsecs_t timestamp) {
-    ALOGE_IF(type >= DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES,
-            "received vsync event for an invalid display (id=%d)", type);
-
+void EventThread::onVSyncEvent(nsecs_t timestamp) {
     Mutex::Autolock _l(mLock);
-    if (type < DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES) {
-        mVSyncEvent[type].header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
-        mVSyncEvent[type].header.id = type;
-        mVSyncEvent[type].header.timestamp = timestamp;
-        mVSyncEvent[type].vsync.count++;
-        mCondition.broadcast();
-    }
+    mVSyncEvent[0].header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
+    mVSyncEvent[0].header.id = 0;
+    mVSyncEvent[0].header.timestamp = timestamp;
+    mVSyncEvent[0].vsync.count++;
+    mCondition.broadcast();
 }
 
 void EventThread::onHotplugReceived(int type, bool connected) {
@@ -308,18 +303,23 @@
 void EventThread::enableVSyncLocked() {
     if (!mUseSoftwareVSync) {
         // never enable h/w VSYNC when screen is off
-        mFlinger->eventControl(DisplayDevice::DISPLAY_PRIMARY,
-                SurfaceFlinger::EVENT_VSYNC, true);
-        mPowerHAL.vsyncHint(true);
+        if (!mVsyncEnabled) {
+            mVsyncEnabled = true;
+            mVSyncSource->setCallback(static_cast<VSyncSource::Callback*>(this));
+            mVSyncSource->setVSyncEnabled(true);
+            mPowerHAL.vsyncHint(true);
+        }
     }
     mDebugVsyncEnabled = true;
 }
 
 void EventThread::disableVSyncLocked() {
-    mFlinger->eventControl(DisplayDevice::DISPLAY_PRIMARY,
-            SurfaceFlinger::EVENT_VSYNC, false);
-    mPowerHAL.vsyncHint(false);
-    mDebugVsyncEnabled = false;
+    if (mVsyncEnabled) {
+        mVsyncEnabled = false;
+        mVSyncSource->setVSyncEnabled(false);
+        mPowerHAL.vsyncHint(false);
+        mDebugVsyncEnabled = false;
+    }
 }
 
 void EventThread::dump(String8& result) const {