intel-virtual-output: Perform an explicit sync

If we fail to track rendering using ShmCompletionEvents and begin to
drop frames, insert an explicit XSync.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/tools/virtual.c b/tools/virtual.c
index 71d18f5..74a03e8 100644 (file)
--- a/tools/virtual.c
+++ b/tools/virtual.c
@@ -1359,8 +1359,14 @@ static int clone_paint(struct clone *c)
                while (XPending(c->dst.dpy))
                        ;
 
-               if (c->dst.serial > LastKnownRequestProcessed(c->dst.dpy))
-                       return EAGAIN;
+               if (c->dst.serial > LastKnownRequestProcessed(c->dst.dpy)) {
+                       if (c->dst.display->send++ == 0)
+                               return EAGAIN;
+
+                       XSync(c->dst.dpy, False);
+                       c->dst.display->flush = 0;
+                       c->dst.display->send = 0;
+               }
        }
 
        if (FORCE_FULL_REDRAW) {