Prevent infinite rhi init failure in basic render loop

Task-number: QTBUG-80365
Change-Id: Iaa2f97b02c4665f0485226d9aa420993330d78f8
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
Reviewed-by: Johan Helsing <johan.helsing@qt.io>

1 files changed, 27 insertions, 7 deletions

diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index da6e524623..5be7fbefe3 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -195,8 +195,16 @@ public:
     bool eventFilter(QObject *watched, QEvent *event) override;
 
     struct WindowData {
+        WindowData()
+            : updatePending(false),
+              grabOnly(false),
+              rhiDeviceLost(false),
+              rhiDoomed(false)
+        { }
         bool updatePending : 1;
         bool grabOnly : 1;
+        bool rhiDeviceLost : 1;
+        bool rhiDoomed : 1;
     };
 
     QHash<QQuickWindow *, WindowData> m_windows;
@@ -362,10 +370,7 @@ QSGGuiThreadRenderLoop::~QSGGuiThreadRenderLoop()
 
 void QSGGuiThreadRenderLoop::show(QQuickWindow *window)
 {
-    WindowData data;
-    data.updatePending = false;
-    data.grabOnly = false;
-    m_windows[window] = data;
+    m_windows[window] = WindowData();
 
     maybeUpdate(window);
 }
@@ -451,8 +456,10 @@ void QSGGuiThreadRenderLoop::handleDeviceLoss()
 
     rc->invalidate();
 
-    for (auto it = m_windows.constBegin(), itEnd = m_windows.constEnd(); it != itEnd; ++it)
+    for (auto it = m_windows.begin(), itEnd = m_windows.end(); it != itEnd; ++it) {
         releaseSwapchain(it.key());
+        it->rhiDeviceLost = true;
+    }
 
     delete rhi;
     rhi = nullptr;
@@ -508,6 +515,13 @@ void QSGGuiThreadRenderLoop::renderWindow(QQuickWindow *window)
     const bool enableRhi = rhiSupport->isRhiEnabled();
 
     if (enableRhi && !rhi) {
+        // This block below handles both the initial QRhi initialization and
+        // also the subsequent reinitialization attempts after a device lost
+        // (reset) situation.
+
+        if (data.rhiDoomed) // no repeated attempts if the initial attempt failed
+            return;
+
         if (!offscreenSurface)
             offscreenSurface = rhiSupport->maybeCreateOffscreenSurface(window);
 
@@ -517,6 +531,8 @@ void QSGGuiThreadRenderLoop::renderWindow(QQuickWindow *window)
             if (rhiSupport->isProfilingRequested())
                 QSGRhiProfileConnection::instance()->initialize(rhi);
 
+            data.rhiDeviceLost = false;
+
             current = true;
             rhi->makeThreadLocalNativeContextCurrent();
 
@@ -533,7 +549,11 @@ void QSGGuiThreadRenderLoop::renderWindow(QQuickWindow *window)
             rcParams.maybeSurface = window;
             cd->context->initialize(&rcParams);
         } else {
-            handleContextCreationFailure(window, false);
+            if (!data.rhiDeviceLost) {
+                data.rhiDoomed = true;
+                handleContextCreationFailure(window, false);
+            }
+            // otherwise no error, will retry on a subsequent rendering attempt
         }
     } else if (!enableRhi && !gl) {
         gl = new QOpenGLContext();
@@ -619,7 +639,7 @@ void QSGGuiThreadRenderLoop::renderWindow(QQuickWindow *window)
         i++;
     }
 
-    // Check for context loss.
+    // Check for context loss. (legacy GL only)
     if (!current && !rhi && !gl->isValid()) {
         for (auto it = m_windows.constBegin() ; it != m_windows.constEnd(); it++) {
             QQuickWindowPrivate *windowPrivate = QQuickWindowPrivate::get(it.key());