6 files changed, 18 insertions, 8 deletions
diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 50777ef03d..0b12b13978 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -430,7 +430,7 @@ void QQuickWindowPrivate::syncSceneGraph()
     if (renderTargetId && !QQuickRenderControl::renderWindowFor(q))
         devicePixelRatio = 1;
 
-    context->prepareSync(devicePixelRatio);
+    context->prepareSync(devicePixelRatio, rhi ? swapchain->currentFrameCommandBuffer() : nullptr);
 
     animationController->beforeNodeSync();
 
diff --git a/src/quick/scenegraph/coreapi/qsgtexture.cpp b/src/quick/scenegraph/coreapi/qsgtexture.cpp
index 715633fdba..418aaca605 100644
--- a/src/quick/scenegraph/coreapi/qsgtexture.cpp
+++ b/src/quick/scenegraph/coreapi/qsgtexture.cpp
@@ -842,11 +842,15 @@ void QSGTexturePrivate::updateRhiTexture(QRhi *rhi, QRhiResourceUpdateBatch *res
 /*!
     \fn bool QSGDynamicTexture::updateTexture()
 
-    Call this function to explicitly update the dynamic texture. Calling bind() will bind
-    the content that was previously updated.
+    Call this function to explicitly update the dynamic texture.
 
     The function returns true if the texture was changed as a resul of the update; otherwise
     returns false.
+
+    \note This function is typically called from QQuickItem::updatePaintNode()
+    or QSGNode::preprocess(), meaning during the \c{synchronization} or the
+    \c{node preprocessing} phases of the scenegraph. Calling it at other times
+    is discouraged and can lead to unexpected behavior.
  */
 
 /*!
diff --git a/src/quick/scenegraph/qsgcontext.cpp b/src/quick/scenegraph/qsgcontext.cpp
index 17eb1e312c..e3c951e5ed 100644
--- a/src/quick/scenegraph/qsgcontext.cpp
+++ b/src/quick/scenegraph/qsgcontext.cpp
@@ -341,9 +341,10 @@ void QSGRenderContext::invalidate()
 {
 }
 
-void QSGRenderContext::prepareSync(qreal devicePixelRatio)
+void QSGRenderContext::prepareSync(qreal devicePixelRatio, QRhiCommandBuffer *cb)
 {
     Q_UNUSED(devicePixelRatio);
+    Q_UNUSED(cb);
 }
 
 void QSGRenderContext::beginNextFrame(QSGRenderer *renderer,
diff --git a/src/quick/scenegraph/qsgcontext_p.h b/src/quick/scenegraph/qsgcontext_p.h
index 244bcfabd1..d389420907 100644
--- a/src/quick/scenegraph/qsgcontext_p.h
+++ b/src/quick/scenegraph/qsgcontext_p.h
@@ -174,7 +174,7 @@ public:
 
     using RenderPassCallback = void (*)(void *);
 
-    virtual void prepareSync(qreal devicePixelRatio);
+    virtual void prepareSync(qreal devicePixelRatio, QRhiCommandBuffer *cb);
     virtual void beginNextFrame(QSGRenderer *renderer,
                                 RenderPassCallback mainPassRecordingStart,
                                 RenderPassCallback mainPassRecordingEnd,
diff --git a/src/quick/scenegraph/qsgdefaultrendercontext.cpp b/src/quick/scenegraph/qsgdefaultrendercontext.cpp
index e8c3ac4abb..b5bf56649b 100644
--- a/src/quick/scenegraph/qsgdefaultrendercontext.cpp
+++ b/src/quick/scenegraph/qsgdefaultrendercontext.cpp
@@ -200,9 +200,14 @@ void QSGDefaultRenderContext::invalidate()
     emit invalidated();
 }
 
-void QSGDefaultRenderContext::prepareSync(qreal devicePixelRatio)
+void QSGDefaultRenderContext::prepareSync(qreal devicePixelRatio, QRhiCommandBuffer *cb)
 {
     m_currentDevicePixelRatio = devicePixelRatio;
+
+    // we store the command buffer already here, in case there is something in
+    // an updatePaintNode() implementation that leads to needing it (for
+    // example, an updateTexture() call on a QSGRhiLayer)
+    m_currentFrameCommandBuffer = cb;
 }
 
 static QBasicMutex qsg_framerender_mutex;
@@ -244,7 +249,7 @@ void QSGDefaultRenderContext::beginNextRhiFrame(QSGRenderer *renderer, QRhiRende
     renderer->setCommandBuffer(cb);
     renderer->setRenderPassRecordingCallbacks(mainPassRecordingStart, mainPassRecordingEnd, callbackUserData);
 
-    m_currentFrameCommandBuffer = cb;
+    m_currentFrameCommandBuffer = cb; // usually the same as what was passed to prepareSync() but cannot count on that having been called
     m_currentFrameRenderPass = rp;
 }
 
diff --git a/src/quick/scenegraph/qsgdefaultrendercontext_p.h b/src/quick/scenegraph/qsgdefaultrendercontext_p.h
index 2fdb3a48dd..97ed681f9a 100644
--- a/src/quick/scenegraph/qsgdefaultrendercontext_p.h
+++ b/src/quick/scenegraph/qsgdefaultrendercontext_p.h
@@ -104,7 +104,7 @@ public:
     void initialize(const QSGRenderContext::InitParams *params) override;
     void invalidate() override;
 
-    void prepareSync(qreal devicePixelRatio) override;
+    void prepareSync(qreal devicePixelRatio, QRhiCommandBuffer *cb) override;
     void beginNextFrame(QSGRenderer *renderer,
                         RenderPassCallback mainPassRecordingStart,
                         RenderPassCallback mainPassRecordingEnd,