ecore - loop time - do not allow setting into the future - not intended

setting a loop time timestamp in the future will lead to all sorts of
bad things. the idea is it was meant to go back a little in time AFTER
some sync/animation etc. event to pretend to be at the time when that
event happend (it just took some time ot arrive at the process) and so
animation and other timelines all agree to be at this time a little
bit in the past. going forwards leads to bad things so disallow it and
complain. this fixes weston in a window problems when it sends
timestamps in the future from weston...

@fix

2 files changed, 28 insertions, 32 deletions

diff --git a/src/lib/ecore/ecore_time.c b/src/lib/ecore/ecore_time.c
index 9f039e2b59..8f3d409e0b 100644
--- a/src/lib/ecore/ecore_time.c
+++ b/src/lib/ecore/ecore_time.c
@@ -79,6 +79,16 @@ ecore_loop_time_get(void)
 EAPI void
 ecore_loop_time_set(double t)
 {
+   double tnow = ecore_time_get();
+   double tdelta = t - tnow;
+
+   if (tdelta > 0.0)
+     {
+        fprintf(stderr,
+                "Eccore: Trying to set loop time (%1.8f) %1.8fs too far in the future\n",
+                t, tdelta);
+        return;
+     }
    efl_loop_time_set(ML_OBJ, t);
 }
 
diff --git a/src/lib/ecore_x/ecore_x_vsync.c b/src/lib/ecore_x/ecore_x_vsync.c
index 1014542a6a..f505193722 100644
--- a/src/lib/ecore_x/ecore_x_vsync.c
+++ b/src/lib/ecore_x/ecore_x_vsync.c
@@ -178,7 +178,7 @@ _fallback_timeout(void *data EINA_UNUSED)
 {
    if (drm_event_is_busy)
      {
-        _drm_send_time(ecore_loop_time_get());
+        _drm_send_time(ecore_time_get());
         return EINA_TRUE;
      }
    fallback_timer = NULL;
@@ -198,7 +198,7 @@ _fail_timeout(void *data EINA_UNUSED)
             (1.0 / 60.0, _fallback_timeout, NULL);
      }
    if (drm_event_is_busy)
-     _drm_send_time(ecore_loop_time_get());
+     _drm_send_time(ecore_time_get());
    return EINA_FALSE;
 }
 
@@ -383,46 +383,32 @@ _drm_vblank_handler(int fd EINA_UNUSED,
         if (pframe != frame)
           {
 #define DELTA_COUNT 10
-             double tnow = ecore_time_get();
              double t = (double)sec + ((double)usec / 1000000);
-             unsigned long long tusec, ptusec;
-             static double tdelta[DELTA_COUNT];
-             static double tdelta_avg = 0.0;
-             static int tdelta_n = 0;
+             unsigned long long tusec, ptusec, tdelt = 0;
              static unsigned int psec = 0, pusec = 0;
 
              tusec = ((unsigned long long)sec) * 1000000 + usec;
              ptusec = ((unsigned long long)psec) * 1000000 + pusec;
              if (tusec <= ptusec)
-               fprintf(stderr,
-                       "EEEEEEK! drm time went backwards! %u.%06u -> %u.%06u\n",
-                       psec, pusec, sec, usec);
-             if (t > tnow)
                {
-                  if (tdelta_n > DELTA_COUNT)
-                    {
-                       t = t + tdelta_avg;
-                    }
-                  else if (tdelta_n < DELTA_COUNT)
-                    {
-                       tdelta[tdelta_n] = tnow - t;
-                       tdelta_n++;
-                       t = tnow;
-                    }
-                  else if (tdelta_n == DELTA_COUNT)
-                    {
-                       int i;
-
-                       for (i = 0; i < DELTA_COUNT; i++)
-                         tdelta_avg += tdelta[i];
-                       tdelta_avg /= (double)(DELTA_COUNT);
-                       tdelta_n++;
-                    }
+                  fprintf(stderr,
+                          "EEEEEEK! drm time went backwards! %u.%06u -> %u.%06u\n",
+                          psec, pusec, sec, usec);
                }
              else
                {
-                  tdelta_avg = 0.0;
-                  tdelta_n = 0;
+                  if (frame > pframe)
+                    {
+                       tdelt = (tusec - ptusec) / (frame - pframe);
+                       // go back in time 1/8th of a frame to account for
+                       // vlnbak gap - this should be enough for now.
+                       // probably need to be a bit more accurate.
+                       // 
+                       // why do this? because the timestamp is the time
+                       // the top-left pixel is first displayed which is
+                       // after the vlbank gap time
+                       t -= (double)(tdelt / 8) / 1000000.0;
+                    }
                }
              _drm_fail_count = 0;
              _drm_send_time(t);