[plasma/kwin/Plasma/6.6] src/backends/drm: backends/drm: release the scanout buffer of virtual layers in beginFrame

Git commit b5be7a6a81eceb33b603d6500d7435bf4e96bdbd by Xaver Hugl.
Committed on 22/07/2026 at 12:55.
Pushed by zamundaaa into branch 'Plasma/6.6'.

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


(cherry picked from commit 05df3e5199ec6f18386456df51d1675eed66da09)

Co-authored-by: Xaver Hugl <[email protected]>

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

https://invent.kde.org/plasma/kwin/-/commit/b5be7a6a81eceb33b603d6500d7435bf4e96bdbd

diff --git a/src/backends/drm/drm_virtual_egl_layer.cpp b/src/backends/drm/drm_virtual_egl_layer.cpp
index 7d7cf4e99b5..4e2ac286b9d 100644
--- a/src/backends/drm/drm_virtual_egl_layer.cpp
+++ b/src/backends/drm/drm_virtual_egl_layer.cpp
@@ -38,7 +38,8 @@ VirtualEglGbmLayer::~VirtualEglGbmLayer()
 
 std::optional<OutputLayerBeginFrameInfo> VirtualEglGbmLayer::doBeginFrame()
 {
-    // gbm surface
+    m_scanoutBuffer.reset();
+
     if (doesGbmSwapchainFit(m_gbmSwapchain.get())) {
         m_oldGbmSwapchain.reset();
         m_oldDamageJournal.clear();