3 files changed, 20 insertions, 6 deletions
diff --git a/src/plugins/platforms/cocoa/qcocoascreen.h b/src/plugins/platforms/cocoa/qcocoascreen.h
index 435a6b95d8f..267da964338 100644
--- a/src/plugins/platforms/cocoa/qcocoascreen.h
+++ b/src/plugins/platforms/cocoa/qcocoascreen.h
@@ -47,7 +47,7 @@ public:
     static NSScreen *nativeScreenForDisplayId(CGDirectDisplayID displayId);
     NSScreen *nativeScreen() const;
 
-    void requestUpdate();
+    bool requestUpdate();
     void deliverUpdateRequests();
     bool isRunningDisplayLink() const;
 
diff --git a/src/plugins/platforms/cocoa/qcocoascreen.mm b/src/plugins/platforms/cocoa/qcocoascreen.mm
index 078d8a1c728..f12f3f8ecc3 100644
--- a/src/plugins/platforms/cocoa/qcocoascreen.mm
+++ b/src/plugins/platforms/cocoa/qcocoascreen.mm
@@ -289,24 +289,33 @@ void QCocoaScreen::update(CGDirectDisplayID displayId)
 
 Q_LOGGING_CATEGORY(lcQpaScreenUpdates, "qt.qpa.screen.updates", QtCriticalMsg);
 
-void QCocoaScreen::requestUpdate()
+bool QCocoaScreen::requestUpdate()
 {
     Q_ASSERT(m_displayId);
 
     if (!isOnline()) {
         qCDebug(lcQpaScreenUpdates) << this << "is not online. Ignoring update request";
-        return;
+        return false;
     }
 
     if (!m_displayLink) {
-        CVDisplayLinkCreateWithCGDisplay(m_displayId, &m_displayLink);
+        qCDebug(lcQpaScreenUpdates) << "Creating display link for" << this;
+        if (CVDisplayLinkCreateWithCGDisplay(m_displayId, &m_displayLink) != kCVReturnSuccess) {
+            qCWarning(lcQpaScreenUpdates) << "Failed to create display link for" << this;
+            return false;
+        }
+        if (auto displayId = CVDisplayLinkGetCurrentCGDisplay(m_displayLink); displayId != m_displayId) {
+            qCWarning(lcQpaScreenUpdates) << "Unexpected display" << displayId << "for display link";
+            CVDisplayLinkRelease(m_displayLink);
+            m_displayLink = nullptr;
+            return false;
+        }
         CVDisplayLinkSetOutputCallback(m_displayLink, [](CVDisplayLinkRef, const CVTimeStamp*,
             const CVTimeStamp*, CVOptionFlags, CVOptionFlags*, void* displayLinkContext) -> int {
                 // FIXME: It would be nice if update requests would include timing info
                 static_cast<QCocoaScreen*>(displayLinkContext)->deliverUpdateRequests();
                 return kCVReturnSuccess;
         }, this);
-        qCDebug(lcQpaScreenUpdates) << "Display link created for" << this;
 
         // During live window resizing -[NSWindow _resizeWithEvent:] will spin a local event loop
         // in event-tracking mode, dequeuing only the mouse drag events needed to update the window's
@@ -361,6 +370,8 @@ void QCocoaScreen::requestUpdate()
         qCDebug(lcQpaScreenUpdates) << "Starting display link for" << this;
         CVDisplayLinkStart(m_displayLink);
     }
+
+    return true;
 }
 
 // Helper to allow building up debug output in multiple steps
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index bb86040481d..205dfbaf9f8 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -1531,7 +1531,10 @@ void QCocoaWindow::requestUpdate()
         << "using" << (updatesWithDisplayLink() ? "display-link" : "timer");
 
     if (updatesWithDisplayLink()) {
-        static_cast<QCocoaScreen *>(screen())->requestUpdate();
+        if (!static_cast<QCocoaScreen *>(screen())->requestUpdate()) {
+            qCDebug(lcQpaDrawing) << "Falling back to timer-based update request";
+            QPlatformWindow::requestUpdate();
+        }
     } else {
         // Fall back to the un-throttled timer-based callback
         QPlatformWindow::requestUpdate();