From 1f71b5a57d4dff4cb6ad21d6a55eef77ed6a3dbe Mon Sep 17 00:00:00 2001
From: Michael Olbrich <m.olbrich@pengutronix.de>
Date: Fri, 13 Apr 2018 09:28:53 +0200
Subject: [PATCH] wayland: don't poll if there are no pending frames

Otherwise the following poll may not return for an arbitrary amount of
time. This can happen if another wayland event queue has flushed and read
our events.

https://bugzilla.gnome.org/show_bug.cgi?id=795224
---
 gst-libs/gst/vaapi/gstvaapiwindow_wayland.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gst-libs/gst/vaapi/gstvaapiwindow_wayland.c b/gst-libs/gst/vaapi/gstvaapiwindow_wayland.c
index 3d77e45668..bd2d89d836 100644
--- a/gst-libs/gst/vaapi/gstvaapiwindow_wayland.c
+++ b/gst-libs/gst/vaapi/gstvaapiwindow_wayland.c
@@ -185,6 +185,11 @@ gst_vaapi_window_wayland_sync (GstVaapiWindow * window)
     if (wl_display_flush (wl_display) < 0)
       goto error;
 
+    if (g_atomic_int_get (&priv->num_frames_pending) == 0) {
+      wl_display_cancel_read (wl_display);
+      return TRUE;
+    }
+
   again:
     if (gst_poll_wait (priv->poll, GST_CLOCK_TIME_NONE) < 0) {
       int saved_errno = errno;