commit 3de6727d7b164859780b9f2eb0e2db98eb8f23f4
author Dominik Laskowski <domlaskowski@google.com> Wed Aug 09 13:15:31 2023 -0400
committer Dominik Laskowski <domlaskowski@google.com> Thu Aug 10 12:48:55 2023 -0400
tree 6c5a73c3e734eaf03bb7f7c604955419c001305d
parent f88c330e870ab4dd333341234836cba4fb209df5

SF: Fix jank after folding due to power sequence

SF assumed that DM always powers off the active display before powering
on the other display. However, this is not the case when simultaneously
folding and pressing the power button to turn on the rear display.

SF then behaves as if all displays were off (e.g. synthetic VSYNC, low
thread priority), causing consistent jank until the next power or fold
event. Fix this by activating the other display if already powered on.

Fixes: 294230902
Test: No jank after simultaneously folding and hitting the power button.
Test: FoldableTest.promotesPacesetterOnConcurrentPowerOff
Change-Id: I5d0bdafc4002ce5ae86866f457132f8a0f178698

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index dddc9b5..c741555 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -5522,18 +5522,22 @@
         // Turn off the display
 
         if (displayId == mActiveDisplayId) {
-            if (setSchedFifo(false) != NO_ERROR) {
-                ALOGW("Failed to set SCHED_OTHER after powering off active display: %s",
-                      strerror(errno));
-            }
-            if (setSchedAttr(false) != NO_ERROR) {
-                ALOGW("Failed set uclamp.min after powering off active display: %s",
-                      strerror(errno));
-            }
+            if (const auto display = getActivatableDisplay()) {
+                onActiveDisplayChangedLocked(activeDisplay.get(), *display);
+            } else {
+                if (setSchedFifo(false) != NO_ERROR) {
+                    ALOGW("Failed to set SCHED_OTHER after powering off active display: %s",
+                          strerror(errno));
+                }
+                if (setSchedAttr(false) != NO_ERROR) {
+                    ALOGW("Failed set uclamp.min after powering off active display: %s",
+                          strerror(errno));
+                }
 
-            if (*currentModeOpt != hal::PowerMode::DOZE_SUSPEND) {
-                mScheduler->disableHardwareVsync(displayId, true);
-                mScheduler->enableSyntheticVsync();
+                if (*currentModeOpt != hal::PowerMode::DOZE_SUSPEND) {
+                    mScheduler->disableHardwareVsync(displayId, true);
+                    mScheduler->enableSyntheticVsync();
+                }
             }
         }
 
@@ -7948,6 +7952,20 @@
     getRenderEngine().onActiveDisplaySizeChanged(activeDisplay.getSize());
 }
 
+sp<DisplayDevice> SurfaceFlinger::getActivatableDisplay() const {
+    if (mPhysicalDisplays.size() == 1) return nullptr;
+
+    // TODO(b/255635821): Choose the pacesetter display, considering both internal and external
+    // displays. For now, pick the other internal display, assuming a dual-display foldable.
+    return findDisplay([this](const DisplayDevice& display) REQUIRES(mStateLock) {
+        const auto idOpt = PhysicalDisplayId::tryCast(display.getId());
+        return idOpt && *idOpt != mActiveDisplayId && display.isPoweredOn() &&
+                mPhysicalDisplays.get(*idOpt)
+                        .transform(&PhysicalDisplay::isInternal)
+                        .value_or(false);
+    });
+}
+
 void SurfaceFlinger::onActiveDisplayChangedLocked(const DisplayDevice* inactiveDisplayPtr,
                                                   const DisplayDevice& activeDisplay) {
     ATRACE_CALL();