layer visibility is sometimes wrong

This discussion started on the mailing list (https://lists.linuxfoundation.org/pipermail/automotive-discussions/2018-February/005682.html) and Kazumasa Mitsunari requested that I create an issue.

I've been trying to run the 5.0.1 demo on an i.MX6 with etnaviv. After
updating libdrm, gstreamer, mesa, meson and wayland to the versions in
OE rocko or master, wayland-ivi-extension to 2.1 and finally agl-
service-windowmanager-2017 to master it mostly works.

One problem I see is that the layer visibilities don't seem to work
consistently:
1. On some boots, the UI is invisible and only "LayerManagerControl set
surface 1 visibility" makes it show up.
2. Even on "good" boots, if I then start an app (which works fine), I
can't switch back to the home screen. Running "LayerManagerControl set
layer 1001 visibility 0" makes it visible again.

As requested by Emre Ucan, I collected some status output:

This is for the problem on startup:
https://gist.github.com/jluebbe/1e7d98ce258f486b209b9c2c7d91a307#file-startup-good-scene-txt
https://gist.github.com/jluebbe/1e7d98ce258f486b209b9c2c7d91a307#file-startup-bad-scene-txt

The difference is:
— startup-bad.scene.txt       2018-02-14 09:29:09.095766870 +0100
+++ startup-good.scene.txt      2018-02-14 09:29:09.131766636 +0100
@@ -24,13 +24,13 @@
 
         surface 1 (0x1)
         ---------------------------------------
-        - created by pid:       444
+        - created by pid:       442
         - original size:      x=1080, y=1920
         - destination region: x=0, y=0, w=1080, h=1920
         - source region:      x=0, y=0, w=1080, h=1920
         - opacity:            1
-        - visibility:         0
-        - frame counter:      2
+        - visibility:         1
+        - frame counter:      13
         - on layer:           1000(0x3e8)
 
     layer 1001 (0x3e9)

In the good case, I then clicked on the Music icon, which worked correctly:
https://gist.github.com/jluebbe/1e7d98ce258f486b209b9c2c7d91a307#file-music-good-scene-txt

Then I clicked on the Home icon, but the music player stayed visible:
https://gist.github.com/jluebbe/1e7d98ce258f486b209b9c2c7d91a307#file-back-to-homescreen-bad-scene-txt