Comment 47 for bug 1189850

(In reply to comment #27)
> (In reply to comment #22)
> > Thanks. In the meantime, I'm going to push the temporary workaround -
> > obviously I still hope to find the real bug.
>
> Is there a way I can help? Attach some debug info or test something?

If you change the define in src/sna/sna_accel.c:

diff --git a/src/sna/sna_accel.c b/src/sna/sna_accel.c
index ae6d3c1..5edad51 100644
--- a/src/sna/sna_accel.c
+++ b/src/sna/sna_accel.c
@@ -57,7 +57,7 @@
 #define FORCE_INPLACE 0
 #define FORCE_FALLBACK 0
 #define FORCE_FLUSH 0
-#define FORCE_FULL_SYNC 1 /* https://bugs.freedesktop.org/show_bug.cgi?id=61628 */
+#define FORCE_FULL_SYNC 0

 #define DEFAULT_TILING I915_TILING_X

that restores the buggy behaviour. If you can keep running with that patch and with --enable-debug to check if any assertions are triggered and see how things progress.