From dbc48c91f92acbef9828afbdf89c7b929d3305ce Mon Sep 17 00:00:00 2001
From: Philipp Knechtges <philipp-dev@knechtges.com>
Date: Thu, 12 Jan 2012 21:01:56 +0100
Subject: [PATCH] kwin: don't wait for vsync when nothing has been painted

---
 scene_opengl_egl.cpp | 5 +++--
 scene_opengl_glx.cpp | 4 +++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/scene_opengl_egl.cpp b/scene_opengl_egl.cpp
index dbda7816a7..7a198b0f6f 100644
--- a/scene_opengl_egl.cpp
+++ b/scene_opengl_egl.cpp
@@ -190,7 +190,9 @@ void SceneOpenGL::paint(QRegion damage, ToplevelList toplevels)
     if (m_overlayWindow->window())  // show the window only after the first pass, since
         m_overlayWindow->show();   // that pass may take long
     lastRenderTime = renderTimer.elapsed();
-    flushBuffer(mask, damage);
+    if (!damage.isEmpty()) {
+        flushBuffer(mask, damage);
+    }
     // do cleanup
     stacking_order.clear();
     checkGLError("PostPaint");
@@ -203,7 +205,6 @@ void SceneOpenGL::waitSync()
 
 void SceneOpenGL::flushBuffer(int mask, QRegion damage)
 {
-    Q_UNUSED(damage)
     glFlush();
     if (mask & PAINT_SCREEN_REGION && surfaceHasSubPost && eglPostSubBufferNV) {
         QRect damageRect = damage.boundingRect();
diff --git a/scene_opengl_glx.cpp b/scene_opengl_glx.cpp
index 84e7f610fe..35f04494de 100644
--- a/scene_opengl_glx.cpp
+++ b/scene_opengl_glx.cpp
@@ -465,7 +465,9 @@ void SceneOpenGL::paint(QRegion damage, ToplevelList toplevels)
     if (m_overlayWindow->window())  // show the window only after the first pass, since
         m_overlayWindow->show();   // that pass may take long
     lastRenderTime = renderTimer.elapsed();
-    flushBuffer(mask, damage);
+    if (!damage.isEmpty()) {
+        flushBuffer(mask, damage);
+    }
     // do cleanup
     stacking_order.clear();
     checkGLError("PostPaint");