Merge "SurfaceFlinger: expose vsync id extra buffers" into sc-dev

10 files changed, 110 insertions, 2 deletions

diff --git a/libs/gui/ISurfaceComposer.cpp b/libs/gui/ISurfaceComposer.cpp
index 10d48a35bf..762746c0ce 100644
--- a/libs/gui/ISurfaceComposer.cpp
+++ b/libs/gui/ISurfaceComposer.cpp
@@ -1235,6 +1235,18 @@ public:
         }
         return reply.readInt32();
     }
+
+    status_t getExtraBufferCount(int* extraBuffers) const override {
+        Parcel data, reply;
+        data.writeInterfaceToken(ISurfaceComposer::getInterfaceDescriptor());
+        status_t err = remote()->transact(BnSurfaceComposer::GET_EXTRA_BUFFER_COUNT, data, &reply);
+        if (err != NO_ERROR) {
+            ALOGE("getExtraBufferCount failed to read data:  %s (%d)", strerror(-err), err);
+            return err;
+        }
+
+        return reply.readInt32(extraBuffers);
+    }
 };
 
 // Out-of-line virtual method definition to trigger vtable emission in this
@@ -2107,6 +2119,16 @@ status_t BnSurfaceComposer::onTransact(
             SAFE_PARCEL(reply->writeInt32, priority);
             return NO_ERROR;
         }
+        case GET_EXTRA_BUFFER_COUNT: {
+            CHECK_INTERFACE(ISurfaceComposer, data, reply);
+            int extraBuffers = 0;
+            int err = getExtraBufferCount(&extraBuffers);
+            if (err != NO_ERROR) {
+                return err;
+            }
+            SAFE_PARCEL(reply->writeInt32, extraBuffers);
+            return NO_ERROR;
+        }
         default: {
             return BBinder::onTransact(code, data, reply, flags);
         }
diff --git a/libs/gui/Surface.cpp b/libs/gui/Surface.cpp
index 59ad8d28bd..07fc0694d6 100644
--- a/libs/gui/Surface.cpp
+++ b/libs/gui/Surface.cpp
@@ -1499,6 +1499,9 @@ int Surface::perform(int operation, va_list args)
     case NATIVE_WINDOW_SET_FRAME_TIMELINE_INFO:
         res = dispatchSetFrameTimelineInfo(args);
         break;
+    case NATIVE_WINDOW_GET_EXTRA_BUFFER_COUNT:
+        res = dispatchGetExtraBufferCount(args);
+        break;
     default:
         res = NAME_NOT_FOUND;
         break;
@@ -1815,6 +1818,14 @@ int Surface::dispatchSetFrameTimelineInfo(va_list args) {
     return setFrameTimelineInfo({frameTimelineVsyncId, inputEventId});
 }
 
+int Surface::dispatchGetExtraBufferCount(va_list args) {
+    ATRACE_CALL();
+    auto extraBuffers = static_cast<int*>(va_arg(args, int*));
+
+    ALOGV("Surface::dispatchGetExtraBufferCount");
+    return getExtraBufferCount(extraBuffers);
+}
+
 bool Surface::transformToDisplayInverse() {
     return (mTransform & NATIVE_WINDOW_TRANSFORM_INVERSE_DISPLAY) ==
             NATIVE_WINDOW_TRANSFORM_INVERSE_DISPLAY;
@@ -2584,4 +2595,8 @@ status_t Surface::setFrameTimelineInfo(const FrameTimelineInfo& frameTimelineInf
     return composerService()->setFrameTimelineInfo(mGraphicBufferProducer, frameTimelineInfo);
 }
 
+status_t Surface::getExtraBufferCount(int* extraBuffers) const {
+    return composerService()->getExtraBufferCount(extraBuffers);
+}
+
 }; // namespace android
diff --git a/libs/gui/include/gui/ISurfaceComposer.h b/libs/gui/include/gui/ISurfaceComposer.h
index 6d1a3ab334..292838e9ae 100644
--- a/libs/gui/include/gui/ISurfaceComposer.h
+++ b/libs/gui/include/gui/ISurfaceComposer.h
@@ -505,6 +505,24 @@ public:
      * Gets priority of the RenderEngine in SurfaceFlinger.
      */
     virtual int getGPUContextPriority() = 0;
+
+    /**
+     * Gets the extra buffers a client would need to allocate if it passes
+     * the Choreographer#getVsyncId with its buffers.
+     *
+     * When Choreographer#getVsyncId is passed to SurfaceFlinger, it is used
+     * as an indication of when to latch the buffer. SurfaceFlinger will make
+     * sure that it will give the app at least the time configured as the
+     * 'appDuration' before trying to latch the buffer.
+     *
+     * The total buffers needed for a given configuration is basically the
+     * numbers of vsyncs a single buffer is used across the stack. For the default
+     * configuration a buffer is held ~1 vsync by the app, ~1 vsync by SurfaceFlinger
+     * and 1 vsync by the display. The extra buffers are calculated as the
+     * number of additional buffers on top of the 3 buffers already allocated
+     * by the app.
+     */
+    virtual status_t getExtraBufferCount(int* extraBuffers) const = 0;
 };
 
 // ----------------------------------------------------------------------------
@@ -567,6 +585,7 @@ public:
         SET_FRAME_TIMELINE_INFO,
         ADD_TRANSACTION_TRACE_LISTENER,
         GET_GPU_CONTEXT_PRIORITY,
+        GET_EXTRA_BUFFER_COUNT,
         // Always append new enum to the end.
     };
 
diff --git a/libs/gui/include/gui/Surface.h b/libs/gui/include/gui/Surface.h
index b6b5c7ca5e..58812214d2 100644
--- a/libs/gui/include/gui/Surface.h
+++ b/libs/gui/include/gui/Surface.h
@@ -189,6 +189,7 @@ public:
 
     virtual status_t setFrameRate(float frameRate, int8_t compatibility, bool shouldBeSeamless);
     virtual status_t setFrameTimelineInfo(const FrameTimelineInfo& info);
+    virtual status_t getExtraBufferCount(int* extraBuffers) const;
 
 protected:
     virtual ~Surface();
@@ -275,6 +276,7 @@ private:
     int dispatchAddQueryInterceptor(va_list args);
     int dispatchGetLastQueuedBuffer(va_list args);
     int dispatchSetFrameTimelineInfo(va_list args);
+    int dispatchGetExtraBufferCount(va_list args);
     bool transformToDisplayInverse();
 
 protected:
diff --git a/libs/gui/tests/Surface_test.cpp b/libs/gui/tests/Surface_test.cpp
index 80e4c770dc..43909ac00d 100644
--- a/libs/gui/tests/Surface_test.cpp
+++ b/libs/gui/tests/Surface_test.cpp
@@ -889,6 +889,8 @@ public:
 
     int getGPUContextPriority() override { return 0; };
 
+    status_t getExtraBufferCount(int* /*extraBuffers*/) const override { return NO_ERROR; }
+
 protected:
     IBinder* onAsBinder() override { return nullptr; }
 
diff --git a/libs/nativewindow/include/system/window.h b/libs/nativewindow/include/system/window.h
index ffe4412b72..7aa2cf4404 100644
--- a/libs/nativewindow/include/system/window.h
+++ b/libs/nativewindow/include/system/window.h
@@ -256,6 +256,7 @@ enum {
     NATIVE_WINDOW_GET_LAST_QUEUED_BUFFER          = 46,    /* private */
     NATIVE_WINDOW_SET_QUERY_INTERCEPTOR           = 47,    /* private */
     NATIVE_WINDOW_SET_FRAME_TIMELINE_INFO         = 48,    /* private */
+    NATIVE_WINDOW_GET_EXTRA_BUFFER_COUNT          = 49,    /* private */
     // clang-format on
 };
 
@@ -1030,6 +1031,11 @@ static inline int native_window_set_frame_timeline_info(struct ANativeWindow* wi
                            frameTimelineVsyncId, inputEventId);
 }
 
+static inline int native_window_get_extra_buffer_count(
+    struct ANativeWindow* window, int* extraBuffers) {
+    return window->perform(window, NATIVE_WINDOW_GET_EXTRA_BUFFER_COUNT, extraBuffers);
+}
+
 // ------------------------------------------------------------------------------------------------
 // Candidates for APEX visibility
 // These functions are planned to be made stable for APEX modules, but have not
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index f785cae6cb..04e9a6d3ff 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -5030,8 +5030,9 @@ status_t SurfaceFlinger::CheckTransactCodeCredentials(uint32_t code) {
         case CAPTURE_DISPLAY:
         case SET_DISPLAY_BRIGHTNESS:
         case SET_FRAME_TIMELINE_INFO:
-        // This is not sensitive information, so should not require permission control.
-        case GET_GPU_CONTEXT_PRIORITY: {
+        case GET_GPU_CONTEXT_PRIORITY:
+        case GET_EXTRA_BUFFER_COUNT: {
+            // This is not sensitive information, so should not require permission control.
             return OK;
         }
         case ADD_REGION_SAMPLING_LISTENER:
@@ -6456,6 +6457,25 @@ int SurfaceFlinger::getGPUContextPriority() {
     return getRenderEngine().getContextPriority();
 }
 
+int SurfaceFlinger::calculateExtraBufferCount(Fps maxSupportedRefreshRate,
+                                              std::chrono::nanoseconds presentLatency) {
+    auto pipelineDepth = presentLatency.count() / maxSupportedRefreshRate.getPeriodNsecs();
+    if (presentLatency.count() % maxSupportedRefreshRate.getPeriodNsecs()) {
+        pipelineDepth++;
+    }
+    return std::max(0ll, pipelineDepth - 2);
+}
+
+status_t SurfaceFlinger::getExtraBufferCount(int* extraBuffers) const {
+    const auto maxSupportedRefreshRate = mRefreshRateConfigs->getSupportedRefreshRateRange().max;
+    const auto vsyncConfig =
+            mVsyncConfiguration->getConfigsForRefreshRate(maxSupportedRefreshRate).late;
+    const auto presentLatency = vsyncConfig.appWorkDuration + vsyncConfig.sfWorkDuration;
+
+    *extraBuffers = calculateExtraBufferCount(maxSupportedRefreshRate, presentLatency);
+    return NO_ERROR;
+}
+
 } // namespace android
 
 #if defined(__gl_h_)
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index ed5b098fb0..a62d0b9a95 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -622,6 +622,8 @@ private:
 
     int getGPUContextPriority() override;
 
+    status_t getExtraBufferCount(int* extraBuffers) const override;
+
     // Implements IBinder::DeathRecipient.
     void binderDied(const wp<IBinder>& who) override;
 
@@ -1052,6 +1054,9 @@ private:
         return std::nullopt;
     }
 
+    static int calculateExtraBufferCount(Fps maxSupportedRefreshRate,
+                                         std::chrono::nanoseconds presentLatency);
+
     sp<StartPropertySetThread> mStartPropertySetThread;
     surfaceflinger::Factory& mFactory;
 
diff --git a/services/surfaceflinger/tests/unittests/SchedulerTest.cpp b/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
index 694790f86a..e46a270ea8 100644
--- a/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
@@ -69,6 +69,8 @@ protected:
     Scheduler::ConnectionHandle mConnectionHandle;
     mock::EventThread* mEventThread;
     sp<MockEventThreadConnection> mEventThreadConnection;
+
+    TestableSurfaceFlinger mFlinger;
 };
 
 SchedulerTest::SchedulerTest() {
@@ -187,4 +189,14 @@ TEST_F(SchedulerTest, onNonPrimaryDisplayModeChanged_invalidParameters) {
     EXPECT_CALL(*mEventThread, onModeChanged(_, _, _)).Times(0);
 }
 
+TEST_F(SchedulerTest, calculateExtraBufferCount) {
+    EXPECT_EQ(0, mFlinger.calculateExtraBufferCount(Fps(60), 30ms));
+    EXPECT_EQ(1, mFlinger.calculateExtraBufferCount(Fps(90), 30ms));
+    EXPECT_EQ(2, mFlinger.calculateExtraBufferCount(Fps(120), 30ms));
+
+    EXPECT_EQ(1, mFlinger.calculateExtraBufferCount(Fps(60), 40ms));
+
+    EXPECT_EQ(0, mFlinger.calculateExtraBufferCount(Fps(60), 10ms));
+}
+
 } // namespace android
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 6aa6d3194d..ce2bfefc44 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -391,6 +391,11 @@ public:
 
     auto getGPUContextPriority() { return mFlinger->getGPUContextPriority(); }
 
+    auto calculateExtraBufferCount(Fps maxSupportedRefreshRate,
+                                   std::chrono::nanoseconds presentLatency) const {
+        return SurfaceFlinger::calculateExtraBufferCount(maxSupportedRefreshRate, presentLatency);
+    }
+
     /* ------------------------------------------------------------------------
      * Read-only access to private data to assert post-conditions.
      */