Improve SurfaceFlinger PTS estimation

Get the next refresh time from DispSync instead of guessing based
on the current time.

Change-Id: I8dc72a3217bfd4e9b4c905034194d1a298cad69a

services/surfaceflinger/DispSync.cpp

@@ -508,4 +508,9 @@ void DispSync::resetErrorLocked() {
     }
 }
 
+nsecs_t DispSync::computeNextRefresh(int periodOffset) const {
+    nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
+    return (((now - mPhase) / mPeriod) + periodOffset + 1) * mPeriod + mPhase;
+}
+
 } // namespace android

services/surfaceflinger/DispSync.h

@@ -83,7 +83,7 @@ public:
     bool addResyncSample(nsecs_t timestamp);
     void endResync();
 
-    // The setPreiod method sets the vsync event model's period to a specific
+    // The setPeriod method sets the vsync event model's period to a specific
     // value.  This should be used to prime the model when a display is first
     // turned on.  It should NOT be used after that.
     void setPeriod(nsecs_t period);
@@ -102,6 +102,12 @@ public:
     // DispSync object.
     status_t removeEventListener(const sp<Callback>& callback);
 
+    // computeNextRefresh computes when the next refresh is expected to begin.
+    // The periodOffset value can be used to move forward or backward; an
+    // offset of zero is the next refresh, -1 is the previous refresh, 1 is
+    // the refresh after next. etc.
+    nsecs_t computeNextRefresh(int periodOffset) const;
+
 private:
 
     void updateModelLocked();

services/surfaceflinger/DisplayHardware/HWComposer.cpp

@@ -821,7 +821,7 @@ status_t HWComposer::setOutputBuffer(int32_t id, const sp<Fence>& acquireFence,
     return NO_ERROR;
 }
 
-sp<Fence> HWComposer::getLastRetireFence(int32_t id) {
+sp<Fence> HWComposer::getLastRetireFence(int32_t id) const {
     if (uint32_t(id)>31 || !mAllocatedDisplayIDs.hasBit(id))
         return Fence::NO_FENCE;
     return mDisplayData[id].lastRetireFence;

services/surfaceflinger/DisplayHardware/HWComposer.h

@@ -142,7 +142,7 @@ public:
     // signal when the h/w composer is completely finished with the frame.
     // For physical displays, it is no longer being displayed. For virtual
     // displays, writes to the output buffer are complete.
-    sp<Fence> getLastRetireFence(int32_t id);
+    sp<Fence> getLastRetireFence(int32_t id) const;
 
     /*
      * Interface to hardware composer's layers functionality.

services/surfaceflinger/Layer.cpp

@@ -1095,7 +1095,8 @@ Region Layer::latchBuffer(bool& recomputeVisibleRegions)
 
         Reject r(mDrawingState, getCurrentState(), recomputeVisibleRegions);
 
-        status_t updateResult = mSurfaceFlingerConsumer->updateTexImage(&r);
+        status_t updateResult = mSurfaceFlingerConsumer->updateTexImage(&r,
+                mFlinger->mPrimaryDispSync);
         if (updateResult == BufferQueue::PRESENT_LATER) {
             // Producer doesn't want buffer to be displayed yet.  Signal a
             // layer update so we check again at the next opportunity.

services/surfaceflinger/SurfaceFlinger.cpp

@@ -2371,6 +2371,15 @@ void SurfaceFlinger::dumpAllLocked(const Vector<String16>& args, size_t& index,
     result.append(SyncFeatures::getInstance().toString());
     result.append("\n");
 
+    colorizer.bold(result);
+    result.append("DispSync configuration: ");
+    colorizer.reset(result);
+    result.appendFormat("app phase %"PRId64" ns, sf phase %"PRId64" ns, "
+            "present offset %d ns (refresh %"PRId64" ns)",
+        vsyncPhaseOffsetNs, sfVsyncPhaseOffsetNs, PRESENT_TIME_OFFSET_FROM_VSYNC_NS,
+        mHwc->getRefreshPeriod(HWC_DISPLAY_PRIMARY));
+    result.append("\n");
+
     /*
      * Dump the visible layer list
      */

services/surfaceflinger/SurfaceFlingerConsumer.cpp

@@ -29,7 +29,8 @@ namespace android {
 
 // ---------------------------------------------------------------------------
 
-status_t SurfaceFlingerConsumer::updateTexImage(BufferRejecter* rejecter)
+status_t SurfaceFlingerConsumer::updateTexImage(BufferRejecter* rejecter,
+        const DispSync& dispSync)
 {
     ATRACE_CALL();
     ALOGV("updateTexImage");
@@ -51,7 +52,7 @@ status_t SurfaceFlingerConsumer::updateTexImage(BufferRejecter* rejecter)
     // Acquire the next buffer.
     // In asynchronous mode the list is guaranteed to be one buffer
     // deep, while in synchronous mode we use the oldest buffer.
-    err = acquireBufferLocked(&item, computeExpectedPresent());
+    err = acquireBufferLocked(&item, computeExpectedPresent(dispSync));
     if (err != NO_ERROR) {
         if (err == BufferQueue::NO_BUFFER_AVAILABLE) {
             err = NO_ERROR;
@@ -128,35 +129,41 @@ sp<NativeHandle> SurfaceFlingerConsumer::getSidebandStream() const {
 // will be slightly later then the actual-present timing.  If we get a
 // desired-present time that is unintentionally a hair after the next
 // vsync, we'll hold the frame when we really want to display it.  We
-// want to use an expected-presentation time that is slightly late to
-// avoid this sort of edge case.
-nsecs_t SurfaceFlingerConsumer::computeExpectedPresent()
+// need to take the offset between actual-present and reported-vsync
+// into account.
+//
+// If the system is configured without a DispSync phase offset for the app,
+// we also want to throw in a bit of padding to avoid edge cases where we
+// just barely miss.  We want to do it here, not in every app.  A major
+// source of trouble is the app's use of the display's ideal refresh time
+// (via Display.getRefreshRate()), which could be off of the actual refresh
+// by a few percent, with the error multiplied by the number of frames
+// between now and when the buffer should be displayed.
+//
+// If the refresh reported to the app has a phase offset, we shouldn't need
+// to tweak anything here.
+nsecs_t SurfaceFlingerConsumer::computeExpectedPresent(const DispSync& dispSync)
 {
-    // Don't yet have an easy way to get actual buffer flip time for
-    // the specific display, so use the current time.  This is typically
-    // 1.3ms past the vsync event time.
-    const nsecs_t prevVsync = systemTime(CLOCK_MONOTONIC);
-
-    // Given a SurfaceFlinger reference, and information about what display
-    // we're destined for, we could query the HWC for the refresh rate.  This
-    // could change over time, e.g. we could switch to 24fps for a movie.
-    // For now, assume 60fps.
-    //const nsecs_t vsyncPeriod =
-    //        getHwComposer().getRefreshPeriod(HWC_DISPLAY_PRIMARY);
-    const nsecs_t vsyncPeriod = 16700000;
-
     // The HWC doesn't currently have a way to report additional latency.
-    // Assume that whatever we submit now will appear on the next flip,
-    // i.e. 1 frame of latency w.r.t. the previous flip.
-    const uint32_t hwcLatency = 1;
+    // Assume that whatever we submit now will appear right after the flip.
+    // For a smart panel this might be 1.  This is expressed in frames,
+    // rather than time, because we expect to have a constant frame delay
+    // regardless of the refresh rate.
+    const uint32_t hwcLatency = 0;
 
-    // A little extra padding to compensate for slack between actual vsync
-    // time and vsync event receipt.  Currently not needed since we're
-    // using "now" instead of a vsync time.
-    const nsecs_t extraPadding = 0;
+    // Ask DispSync when the next refresh will be (CLOCK_MONOTONIC).
+    const nsecs_t nextRefresh = dispSync.computeNextRefresh(hwcLatency);
 
-    // Total it up.
-    return prevVsync + hwcLatency * vsyncPeriod + extraPadding;
+    // The DispSync time is already adjusted for the difference between
+    // vsync and reported-vsync (PRESENT_TIME_OFFSET_FROM_VSYNC_NS), so
+    // we don't need to factor that in here.  Pad a little to avoid
+    // weird effects if apps might be requesting times right on the edge.
+    nsecs_t extraPadding = 0;
+    if (VSYNC_EVENT_PHASE_OFFSET_NS == 0) {
+        extraPadding = 1000000;        // 1ms (6% of 60Hz)
+    }
+
+    return nextRefresh + extraPadding;
 }
 
 void SurfaceFlingerConsumer::setContentsChangedListener(

services/surfaceflinger/SurfaceFlingerConsumer.h

@@ -17,6 +17,7 @@
 #ifndef ANDROID_SURFACEFLINGERCONSUMER_H
 #define ANDROID_SURFACEFLINGERCONSUMER_H
 
+#include "DispSync.h"
 #include <gui/GLConsumer.h>
 
 namespace android {
@@ -33,7 +34,8 @@ public:
 
     SurfaceFlingerConsumer(const sp<IGraphicBufferConsumer>& consumer,
             uint32_t tex)
-        : GLConsumer(consumer, tex, GLConsumer::TEXTURE_EXTERNAL, false)
+        : GLConsumer(consumer, tex, GLConsumer::TEXTURE_EXTERNAL, false),
+          mTransformToDisplayInverse(false)
     {}
 
     class BufferRejecter {
@@ -51,7 +53,7 @@ public:
     // reject the newly acquired buffer.  Unlike the GLConsumer version,
     // this does not guarantee that the buffer has been bound to the GL
     // texture.
-    status_t updateTexImage(BufferRejecter* rejecter);
+    status_t updateTexImage(BufferRejecter* rejecter, const DispSync& dispSync);
 
     // See GLConsumer::bindTextureImageLocked().
     status_t bindTextureImage();
@@ -66,7 +68,7 @@ public:
     sp<NativeHandle> getSidebandStream() const;
 
 private:
-    nsecs_t computeExpectedPresent();
+    nsecs_t computeExpectedPresent(const DispSync& dispSync);
 
     virtual void onSidebandStreamChanged();