From 2a185dd22ddb5b0d7d2ef5948591028766bb9530 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michel=20D=C3=A4nzer?= <mdaenzer@redhat.com>
Date: Mon, 2 Mar 2020 18:09:31 +0100
Subject: [PATCH xserver 19/22] xwayland: Use frame callbacks for Present
 vblank events

Instead of only the fallback timer.

Fixes https://gitlab.freedesktop.org/xorg/xserver/issues/854

v2:
* Drop unused frame_callback member of struct xwl_present_window
  (Olivier Fourdan)

Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>
(cherry picked from commit 9b31358c52e951883bf7c01c953a9da080542244)
---
 hw/xwayland/xwayland-present.c | 22 ++++++++++++++--------
 hw/xwayland/xwayland.h         |  2 --
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/hw/xwayland/xwayland-present.c b/hw/xwayland/xwayland-present.c
index baa97d6f3..c7c077aaa 100644
--- a/hw/xwayland/xwayland-present.c
+++ b/hw/xwayland/xwayland-present.c
@@ -242,7 +242,10 @@ xwl_present_timer_callback(OsTimerPtr timer,
 {
     struct xwl_present_window *xwl_present_window = arg;
 
-    xwl_present_window->frame_timer_firing = TRUE;
+    /* If we were expecting a frame callback for this window, it didn't arrive
+     * in a second. Stop listening to it to avoid double-bumping the MSC
+     */
+    xorg_list_del(&xwl_present_window->frame_callback_list);
 
     xwl_present_msc_bump(xwl_present_window);
     xwl_present_reset_timer(xwl_present_window);
@@ -255,11 +258,6 @@ xwl_present_frame_callback(struct xwl_present_window *xwl_present_window)
 {
     xorg_list_del(&xwl_present_window->frame_callback_list);
 
-    if (xwl_present_window->frame_timer_firing) {
-        /* If the timer is firing, this frame callback is too late */
-        return;
-    }
-
     xwl_present_msc_bump(xwl_present_window);
 
     /* we do not need the timer anymore for this frame,
@@ -349,6 +347,7 @@ xwl_present_queue_vblank(WindowPtr present_window,
                          uint64_t msc)
 {
     struct xwl_present_window *xwl_present_window = xwl_present_window_get_priv(present_window);
+    struct xwl_window *xwl_window = xwl_window_from_window(present_window);
     struct xwl_present_event *event;
 
     event = malloc(sizeof *event);
@@ -361,7 +360,15 @@ xwl_present_queue_vblank(WindowPtr present_window,
 
     xorg_list_append(&event->list, &xwl_present_window->event_list);
 
-    if (!xwl_present_window->frame_timer)
+    /* If there's a pending frame callback, use that */
+    if (xwl_window && xwl_window->frame_callback &&
+        xorg_list_is_empty(&xwl_present_window->frame_callback_list)) {
+        xorg_list_add(&xwl_present_window->frame_callback_list,
+                      &xwl_window->frame_callback_list);
+    }
+
+    if ((xwl_window && xwl_window->frame_callback) ||
+        !xwl_present_window->frame_timer)
         xwl_present_reset_timer(xwl_present_window);
 
     return Success;
@@ -486,7 +493,6 @@ xwl_present_flip(WindowPtr present_window,
     }
 
     /* Realign timer */
-    xwl_present_window->frame_timer_firing = FALSE;
     xwl_present_reset_timer(xwl_present_window);
 
     wl_surface_damage(xwl_window->surface, 0, 0,
diff --git a/hw/xwayland/xwayland.h b/hw/xwayland/xwayland.h
index d4eb6bf1a..a12ec257b 100644
--- a/hw/xwayland/xwayland.h
+++ b/hw/xwayland/xwayland.h
@@ -199,9 +199,7 @@ struct xwl_present_window {
     uint64_t ust;
 
     OsTimerPtr frame_timer;
-    Bool frame_timer_firing;
 
-    struct wl_callback *frame_callback;
     struct wl_callback *sync_callback;
 
     struct xorg_list event_list;
-- 
2.24.1