SF: give a higher score to frame rates which exact matches

To avoid cases where devices with very close refresh rates
(such as 53Hz and 55Hz) gives the same score for these,
assign a small (0.99) factor to frame rate that are
not exact match of a multiple of the refresh rate

Test: atest FrameRateCtsActivity
Test: atest RefreshRateConfigsTest
Bug: 190578904
Change-Id: Idd32600ccacc0cad8f44c9d9373e50a333663717
Merged-In: Idd32600ccacc0cad8f44c9d9373e50a333663717

3 files changed, 80 insertions, 24 deletions

diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp b/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
index 74ffc8fb9c..661b6c8d43 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
@@ -134,27 +134,10 @@ bool RefreshRateConfigs::isVoteAllowed(const LayerRequirement& layer,
     return true;
 }
 
-float RefreshRateConfigs::calculateLayerScoreLocked(const LayerRequirement& layer,
-                                                    const RefreshRate& refreshRate,
-                                                    bool isSeamlessSwitch) const {
-    if (!isVoteAllowed(layer, refreshRate)) {
-        return 0;
-    }
-
+float RefreshRateConfigs::calculateNonExactMatchingLayerScoreLocked(
+        const LayerRequirement& layer, const RefreshRate& refreshRate) const {
     constexpr float kScoreForFractionalPairs = .8f;
 
-    // Slightly prefer seamless switches.
-    constexpr float kSeamedSwitchPenalty = 0.95f;
-    const float seamlessness = isSeamlessSwitch ? 1.0f : kSeamedSwitchPenalty;
-
-    // If the layer wants Max, give higher score to the higher refresh rate
-    if (layer.vote == LayerVoteType::Max) {
-        const auto ratio = refreshRate.getFps().getValue() /
-                mAppRequestRefreshRates.back()->getFps().getValue();
-        // use ratio^2 to get a lower score the more we get further from peak
-        return ratio * ratio;
-    }
-
     const auto displayPeriod = refreshRate.getVsyncPeriod();
     const auto layerPeriod = layer.desiredRefreshRate.getPeriodNsecs();
     if (layer.vote == LayerVoteType::ExplicitDefault) {
@@ -179,7 +162,7 @@ float RefreshRateConfigs::calculateLayerScoreLocked(const LayerRequirement& laye
     if (layer.vote == LayerVoteType::ExplicitExactOrMultiple ||
         layer.vote == LayerVoteType::Heuristic) {
         if (isFractionalPairOrMultiple(refreshRate.getFps(), layer.desiredRefreshRate)) {
-            return kScoreForFractionalPairs * seamlessness;
+            return kScoreForFractionalPairs;
         }
 
         // Calculate how many display vsyncs we need to present a single frame for this
@@ -189,7 +172,7 @@ float RefreshRateConfigs::calculateLayerScoreLocked(const LayerRequirement& laye
         static constexpr size_t MAX_FRAMES_TO_FIT = 10; // Stop calculating when score < 0.1
         if (displayFramesRemainder == 0) {
             // Layer desired refresh rate matches the display rate.
-            return 1.0f * seamlessness;
+            return 1.0f;
         }
 
         if (displayFramesQuotient == 0) {
@@ -207,7 +190,29 @@ float RefreshRateConfigs::calculateLayerScoreLocked(const LayerRequirement& laye
             iter++;
         }
 
-        return (1.0f / iter) * seamlessness;
+        return (1.0f / iter);
+    }
+
+    return 0;
+}
+
+float RefreshRateConfigs::calculateLayerScoreLocked(const LayerRequirement& layer,
+                                                    const RefreshRate& refreshRate,
+                                                    bool isSeamlessSwitch) const {
+    if (!isVoteAllowed(layer, refreshRate)) {
+        return 0;
+    }
+
+    // Slightly prefer seamless switches.
+    constexpr float kSeamedSwitchPenalty = 0.95f;
+    const float seamlessness = isSeamlessSwitch ? 1.0f : kSeamedSwitchPenalty;
+
+    // If the layer wants Max, give higher score to the higher refresh rate
+    if (layer.vote == LayerVoteType::Max) {
+        const auto ratio = refreshRate.getFps().getValue() /
+                mAppRequestRefreshRates.back()->getFps().getValue();
+        // use ratio^2 to get a lower score the more we get further from peak
+        return ratio * ratio;
     }
 
     if (layer.vote == LayerVoteType::ExplicitExact) {
@@ -222,7 +227,18 @@ float RefreshRateConfigs::calculateLayerScoreLocked(const LayerRequirement& laye
         return divider == 1;
     }
 
-    return 0;
+    // If the layer frame rate is a divider of the refresh rate it should score
+    // the highest score.
+    if (getFrameRateDivider(refreshRate.getFps(), layer.desiredRefreshRate) > 0) {
+        return 1.0f * seamlessness;
+    }
+
+    // The layer frame rate is not a divider of the refresh rate,
+    // there is a small penalty attached to the score to favor the frame rates
+    // the exactly matches the display refresh rate or a multiple.
+    constexpr float kNonExactMatchingPenalty = 0.99f;
+    return calculateNonExactMatchingLayerScoreLocked(layer, refreshRate) * seamlessness *
+            kNonExactMatchingPenalty;
 }
 
 struct RefreshRateScore {
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
index 49da973c24..99f217c2e2 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
@@ -450,6 +450,9 @@ private:
     float calculateLayerScoreLocked(const LayerRequirement&, const RefreshRate&,
                                     bool isSeamlessSwitch) const REQUIRES(mLock);
 
+    float calculateNonExactMatchingLayerScoreLocked(const LayerRequirement&,
+                                                    const RefreshRate&) const REQUIRES(mLock);
+
     void updateDisplayModes(const DisplayModes& mode, DisplayModeId currentModeId) EXCLUDES(mLock);
 
     void initializeIdleTimer();
diff --git a/services/surfaceflinger/tests/unittests/RefreshRateConfigsTest.cpp b/services/surfaceflinger/tests/unittests/RefreshRateConfigsTest.cpp
index 9d63d995d9..d8c9babac3 100644
--- a/services/surfaceflinger/tests/unittests/RefreshRateConfigsTest.cpp
+++ b/services/surfaceflinger/tests/unittests/RefreshRateConfigsTest.cpp
@@ -175,7 +175,6 @@ protected:
     RefreshRate mExpected30Config = {mConfig30, RefreshRate::ConstructorTag(0)};
     RefreshRate mExpected120Config = {mConfig120, RefreshRate::ConstructorTag(0)};
 
-private:
     DisplayModePtr createDisplayMode(DisplayModeId modeId, int32_t group, int64_t vsyncPeriod,
                                      ui::Size resolution = ui::Size());
 };
@@ -2170,6 +2169,44 @@ TEST_F(RefreshRateConfigsTest, getBestRefreshRate_FractionalRefreshRates_ExactAn
               refreshRateConfigs->getBestRefreshRate(layers, {.touch = false, .idle = false}));
 }
 
+// b/190578904
+TEST_F(RefreshRateConfigsTest, getBestRefreshRate_deviceWithCloseRefreshRates) {
+    constexpr int kMinRefreshRate = 10;
+    constexpr int kMaxRefreshRate = 240;
+
+    DisplayModes displayModes;
+    for (int fps = kMinRefreshRate; fps < kMaxRefreshRate; fps++) {
+        constexpr int32_t kGroup = 0;
+        const auto refreshRate = Fps(static_cast<float>(fps));
+        displayModes.push_back(
+                createDisplayMode(DisplayModeId(fps), kGroup, refreshRate.getPeriodNsecs()));
+    }
+
+    const RefreshRateConfigs::GlobalSignals globalSignals = {.touch = false, .idle = false};
+    auto refreshRateConfigs =
+            std::make_unique<RefreshRateConfigs>(displayModes,
+                                                 /*currentConfigId=*/displayModes[0]->getId());
+
+    auto layers = std::vector<LayerRequirement>{LayerRequirement{.weight = 1.0f}};
+    const auto testRefreshRate = [&](Fps fps, LayerVoteType vote) {
+        layers[0].desiredRefreshRate = fps;
+        layers[0].vote = vote;
+        EXPECT_EQ(fps.getIntValue(),
+                  refreshRateConfigs->getBestRefreshRate(layers, globalSignals)
+                          .getFps()
+                          .getIntValue())
+                << "Failed for " << RefreshRateConfigs::layerVoteTypeString(vote);
+    };
+
+    for (int fps = kMinRefreshRate; fps < kMaxRefreshRate; fps++) {
+        const auto refreshRate = Fps(static_cast<float>(fps));
+        testRefreshRate(refreshRate, LayerVoteType::Heuristic);
+        testRefreshRate(refreshRate, LayerVoteType::ExplicitDefault);
+        testRefreshRate(refreshRate, LayerVoteType::ExplicitExactOrMultiple);
+        testRefreshRate(refreshRate, LayerVoteType::ExplicitExact);
+    }
+}
+
 TEST_F(RefreshRateConfigsTest, testComparisonOperator) {
     EXPECT_TRUE(mExpected60Config < mExpected90Config);
     EXPECT_FALSE(mExpected60Config < mExpected60Config);