SF: Don't bump to PERFORMANCE refresh rate with infrequent updates
Testing scenario:
1. Set brightness around 50%-55%, set dark theme.
2. Open Chrome.
3. Click search bar.
4. Can see the cursor show up.
Notice the flickering of the screen.
Explanation:
Kernel idle timer detects inactivity after 100ms, and turns the refresh rate to 60Hz.
When a cursor update happens (every 500ms), SF receives a new frame, notifies kernel,
the refresh rate bumps to 90Hz. After 100ms the kernel again decreases the refresh rate to 60Hz.
Desired goals:
Stop the flickering (eg. changing between 60-90Hz too often).
Continue having low battery impact.
Solution in this AG:
Add logic to SF to detect infrequent updates (for all layers). Description of the algorithm:
1) Store the timestamp of the last two buffers.
2) If the first buffer is older than 250 ms, detect inactivity, go into DEFAULT refresh rate.
3) EXIT: on touch event, layer requests 2 or more frames in less than 250ms.
NOTE: if the application is explicitly requesting 90Hz, SF does not override that. Idle kernel
still kicks in, and the flickering happens.
tested on Chrome v74 Beta, and messaging app.
Test: manual, b/135009095
Bug: 135718869
Change-Id: I72d8cd48b3ec900989afcf0fab1cdc3046b87274
diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index bb24f73..99d6fae 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -330,8 +330,11 @@
: RefreshRateType::PERFORMANCE;
const auto refreshRate = mRefreshRateConfigs.getRefreshRate(refreshRateType);
- const uint32_t fps = (refreshRate) ? refreshRate->fps : 0;
- return mLayerHistory.createLayer(name, fps);
+ const uint32_t performanceFps = (refreshRate) ? refreshRate->fps : 0;
+
+ const auto defaultRefreshRate = mRefreshRateConfigs.getRefreshRate(RefreshRateType::DEFAULT);
+ const uint32_t defaultFps = (defaultRefreshRate) ? defaultRefreshRate->fps : 0;
+ return mLayerHistory.createLayer(name, defaultFps, performanceFps);
}
void Scheduler::addLayerPresentTimeAndHDR(