commit be0f948bd3b780e1a70e57eb01113ec897f99264
author Ady Abraham <adyabr@google.com> Wed Apr 24 15:41:53 2019 -0700
committer Ady Abraham <adyabr@google.com> Mon Apr 29 18:01:19 2019 -0700
tree 7670d86fdea1997faae5a87921e7b241cca65b9e
parent dde87c4a326d0480aef0420f04c160b9d5d5096e

SurfaceFlinger: support negative phase offset

Store the last 2 present frames to accommodate negative phase offsets.

Test: systrace
Bug: 130191039
Change-Id: Ie4460d4a1b14a2a12f5d2f3c1542e0b837cb761c

services/surfaceflinger/Scheduler/PhaseOffsets.cpp

diff --git a/services/surfaceflinger/Scheduler/PhaseOffsets.cpp b/services/surfaceflinger/Scheduler/PhaseOffsets.cpp
index 16f6729..276bce1 100644
--- a/services/surfaceflinger/Scheduler/PhaseOffsets.cpp
+++ b/services/surfaceflinger/Scheduler/PhaseOffsets.cpp
@@ -65,6 +65,13 @@
     property_get("debug.sf.high_fps_late_sf_phase_offset_ns", value, "1000000");
     const int highFpsLateSfOffsetNs = atoi(value);
 
+    // Below defines the threshold when an offset is considered to be negative, i.e. targeting
+    // for the N+2 vsync instead of N+1. This means that:
+    // For offset < threshold, SF wake up (vsync_duration - offset) before HW vsync.
+    // For offset >= threshold, SF wake up (2 * vsync_duration - offset) before HW vsync.
+    property_get("debug.sf.phase_offset_threshold_for_next_vsync_ns", value, "-1");
+    const int phaseOffsetThresholdForNextVsyncNs = atoi(value);
+
     mDefaultRefreshRateOffsets.early = {earlySfOffsetNs != -1 ? earlySfOffsetNs
                                                               : sfVsyncPhaseOffsetNs,
                                         earlyAppOffsetNs != -1 ? earlyAppOffsetNs
@@ -84,6 +91,10 @@
                                        highFpsEarlyGlAppOffsetNs != -1 ? highFpsEarlyGlAppOffsetNs
                                                                        : highFpsLateAppOffsetNs};
     mHighRefreshRateOffsets.late = {highFpsLateSfOffsetNs, highFpsLateAppOffsetNs};
+
+    mOffsetThresholdForNextVsync = phaseOffsetThresholdForNextVsyncNs != -1
+            ? phaseOffsetThresholdForNextVsyncNs
+            : std::numeric_limits<nsecs_t>::max();
 }
 
 PhaseOffsets::Offsets PhaseOffsets::getOffsetsForRefreshRate(

services/surfaceflinger/Scheduler/PhaseOffsets.h

diff --git a/services/surfaceflinger/Scheduler/PhaseOffsets.h b/services/surfaceflinger/Scheduler/PhaseOffsets.h
index 08747a5..dc71e6e 100644
--- a/services/surfaceflinger/Scheduler/PhaseOffsets.h
+++ b/services/surfaceflinger/Scheduler/PhaseOffsets.h
@@ -46,6 +46,7 @@
             RefreshRateConfigs::RefreshRateType refreshRateType) const = 0;
     virtual Offsets getCurrentOffsets() const = 0;
     virtual void setRefreshRateType(RefreshRateConfigs::RefreshRateType refreshRateType) = 0;
+    virtual nsecs_t getOffsetThresholdForNextVsync() const = 0;
     virtual void dump(std::string& result) const = 0;
 };
 
@@ -72,6 +73,8 @@
         mRefreshRateType = refreshRateType;
     }
 
+    nsecs_t getOffsetThresholdForNextVsync() const override { return mOffsetThresholdForNextVsync; }
+
     // Returns current offsets in human friendly format.
     void dump(std::string& result) const override;
 
@@ -84,6 +87,7 @@
 
     Offsets mDefaultRefreshRateOffsets;
     Offsets mHighRefreshRateOffsets;
+    nsecs_t mOffsetThresholdForNextVsync;
 };
 } // namespace impl
 

services/surfaceflinger/Scheduler/VSyncModulator.h

diff --git a/services/surfaceflinger/Scheduler/VSyncModulator.h b/services/surfaceflinger/Scheduler/VSyncModulator.h
index 1a0de08..81a7864 100644
--- a/services/surfaceflinger/Scheduler/VSyncModulator.h
+++ b/services/surfaceflinger/Scheduler/VSyncModulator.h
@@ -139,6 +139,19 @@
         }
     }
 
+    Offsets getOffsets() {
+        // Early offsets are used if we're in the middle of a refresh rate
+        // change, or if we recently begin a transaction.
+        if (mTransactionStart == Scheduler::TransactionStart::EARLY ||
+            mRemainingEarlyFrameCount > 0 || mRefreshRateChangePending) {
+            return mEarlyOffsets;
+        } else if (mLastFrameUsedRenderEngine) {
+            return mEarlyGlOffsets;
+        } else {
+            return mLateOffsets;
+        }
+    }
+
 private:
     void updateOffsets() {
         const Offsets desired = getOffsets();
@@ -167,19 +180,6 @@
         }
     }
 
-    Offsets getOffsets() {
-        // Early offsets are used if we're in the middle of a refresh rate
-        // change, or if we recently begin a transaction.
-        if (mTransactionStart == Scheduler::TransactionStart::EARLY ||
-            mRemainingEarlyFrameCount > 0 || mRefreshRateChangePending) {
-            return mEarlyOffsets;
-        } else if (mLastFrameUsedRenderEngine) {
-            return mEarlyGlOffsets;
-        } else {
-            return mLateOffsets;
-        }
-    }
-
     Offsets mLateOffsets;
     Offsets mEarlyOffsets;
     Offsets mEarlyGlOffsets;