[PATCH xserver 2/3] present: Requeue if flip driver hook fails and target MSC not reached

[Michel Dänzer]

From: Michel Dänzer <michel.daenzer at amd.com>

For flipping, we wait for the MSC before the target MSC and then call
the driver flip hook. If the latter fails, we have to wait for the
target MSC before falling back to a copy, or else it's executed too
early.

Fixes glxgears running at unbounded framerate (not synchronized to the
refresh rate) in fullscreen if the driver flip hook fails.

Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
---
 present/present.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/present/present.c b/present/present.c
index 44d6c9e..824ca56 100644
--- a/present/present.c
+++ b/present/present.c
@@ -721,6 +721,20 @@ present_execute(present_vblank_ptr vblank, uint64_t ust, uint64_t crtc_msc)
             if (window == screen_priv->flip_window)
                 present_unflip(screen);
         }
+
+        /* If present_flip failed, we may have to requeue for the target MSC */
+        if (msc_is_after(vblank->target_msc, crtc_msc) &&
+            Success == present_queue_vblank(screen,
+                                            vblank->crtc,
+                                            vblank->event_id,
+                                            vblank->target_msc)) {
+            xorg_list_add(&vblank->event_queue, &present_exec_queue);
+            xorg_list_append(&vblank->window_list,
+                             &present_get_window_priv(window, TRUE)->vblank);
+            vblank->queued = TRUE;
+            return;
+        }
+
         present_copy_region(&window->drawable, vblank->pixmap, vblank->update, vblank->x_off, vblank->y_off);
 
         /* present_copy_region sticks the region into a scratch GC,
-- 
2.7.0