3 files changed, 16 insertions, 8 deletions

diff --git a/xorg-server/present/present.c b/xorg-server/present/present.c
index 3aea0d7c6..f488e21cc 100644
--- a/xorg-server/present/present.c
+++ b/xorg-server/present/present.c
@@ -291,14 +291,18 @@ present_window_to_crtc_msc(WindowPtr window, RRCrtcPtr crtc, uint64_t window_msc
     if (crtc != window_priv->crtc) {
         uint64_t        old_ust, old_msc;
 
-        /* The old CRTC may have been turned off, in which case
-         * we'll just use whatever previous MSC we'd seen from this CRTC
-         */
+        if (window_priv->crtc == PresentCrtcNeverSet) {
+            window_priv->msc_offset = 0;
+        } else {
+            /* The old CRTC may have been turned off, in which case
+             * we'll just use whatever previous MSC we'd seen from this CRTC
+             */
 
-        if (present_get_ust_msc(window->drawable.pScreen, window_priv->crtc, &old_ust, &old_msc) != Success)
-            old_msc = window_priv->msc;
+            if (present_get_ust_msc(window->drawable.pScreen, window_priv->crtc, &old_ust, &old_msc) != Success)
+                old_msc = window_priv->msc;
 
-        window_priv->msc_offset += new_msc - old_msc;
+            window_priv->msc_offset += new_msc - old_msc;
+        }
         window_priv->crtc = crtc;
     }
 
@@ -395,7 +399,8 @@ present_set_abort_flip(ScreenPtr screen)
         present_set_tree_pixmap(screen_priv->flip_window,
                                   (*screen->GetScreenPixmap)(screen));
 
-    present_set_tree_pixmap(screen->root, (*screen->GetScreenPixmap)(screen));
+    if (screen->root)
+        present_set_tree_pixmap(screen->root, (*screen->GetScreenPixmap)(screen));
 
     screen_priv->flip_pending->abort_flip = TRUE;
 }
@@ -725,7 +730,7 @@ present_pixmap(WindowPtr window,
         if (!pixmap)
             target_crtc = window_priv->crtc;
 
-        if (!target_crtc)
+        if (!target_crtc || target_crtc == PresentCrtcNeverSet)
             target_crtc = present_get_crtc(window);
     }
 
diff --git a/xorg-server/present/present_priv.h b/xorg-server/present/present_priv.h
index d8569a2b6..f5c1652d1 100644
--- a/xorg-server/present/present_priv.h
+++ b/xorg-server/present/present_priv.h
@@ -134,6 +134,8 @@ typedef struct present_window_priv {
     struct xorg_list       notifies;
 } present_window_priv_rec, *present_window_priv_ptr;
 
+#define PresentCrtcNeverSet     ((RRCrtcPtr) 1)
+
 extern DevPrivateKeyRec present_window_private_key;
 
 static inline present_window_priv_ptr
diff --git a/xorg-server/present/present_screen.c b/xorg-server/present/present_screen.c
index 25ef6818d..2f91ac7dc 100644
--- a/xorg-server/present/present_screen.c
+++ b/xorg-server/present/present_screen.c
@@ -45,6 +45,7 @@ present_get_window_priv(WindowPtr window, Bool create)
         return NULL;
     xorg_list_init(&window_priv->vblank);
     xorg_list_init(&window_priv->notifies);
+    window_priv->crtc = PresentCrtcNeverSet;
     dixSetPrivate(&window->devPrivates, &present_window_private_key, window_priv);
     return window_priv;
 }