[plasma/kwin] src/backends/drm: backends/drm: release the scanout buffer of virtual layers in beginFrame

Git commit 05df3e5199ec6f18386456df51d1675eed66da09 by Xaver Hugl.
Committed on 22/07/2026 at 11:01.
Pushed by zamundaaa into branch 'master'.

backends/drm: release the scanout buffer of virtual layers in beginFrame

Otherwise we just keep the client buffer until the next scanout cycle, which is
quite broken.

BUG: 523353

M  +2    -1    src/backends/drm/drm_virtual_egl_layer.cpp

https://invent.kde.org/plasma/kwin/-/commit/05df3e5199ec6f18386456df51d1675eed66da09

diff --git a/src/backends/drm/drm_virtual_egl_layer.cpp b/src/backends/drm/drm_virtual_egl_layer.cpp
index c2ca5980e49..7837f58ea80 100644
--- a/src/backends/drm/drm_virtual_egl_layer.cpp
+++ b/src/backends/drm/drm_virtual_egl_layer.cpp
@@ -40,7 +40,8 @@ VirtualEglGbmLayer::~VirtualEglGbmLayer()
 
 std::optional<OutputLayerBeginFrameInfo> VirtualEglGbmLayer::doBeginFrame()
 {
-    // gbm surface
+    m_scanoutBuffer.reset();
+
     if (doesGbmSwapchainFit(m_gbmSwapchain.get())) {
         m_oldGbmSwapchain.reset();
         m_oldDamageJournal.clear();