Public bug reported:
I've got a dual display setup, with one monitor rotated and I've been
running into some weird bugs. The screen will not update properly at
times and there will be areas that will intermittently flicker and show
old areas that should have been overdrawn.
Once it starts doing this, the only way to get things back to normal is
to reboot.
Going into standby and coming out of standby won't fix it. Actually,
sometimes coming out of standby the screen won't refresh properly and
I'll see the whole screen get some triple-buffer epilepsy inducing
flicker.
When I move the mouse from screen to screen and hover over the ubuntu launcher
dock so that it scrolls the icons it will flip the triple buffers and the areas
that have old data flickers.
I think the display is triple buffered and one of the buffers gets old
data. I can refresh the screen by dragging windows around manually like
an "eraser" where I'm using the window to "erase old data" but this
tends to get super annoying.
It seems to get brought out by rotating one of my displays. I have a
1920x1200 pivoting display that is rotated to the left. My other
display is 1920x1080 normal at position +1200+364.
I seem to hit this a lot because my monitor doesn't have a good EDID so it
comes up in ubuntu with an error message about crtcs (since it wants to do a
1920x1080 and it thinks the max is 1024x768) so after I set a new mode with:
$ xrandr --newmode "1920x1080R" 138.50 1920 1968 2000 2080 1080 1083
1088 1111 +hsync -vsync; xrandr --addmode VGA-1 "1920x1080R"
Once the new mode gets added Ubuntu will automatically restore my desktop to
its old settings pre-reboot and I start getting the flicker/update problems.
I would imagine that the bug should show itself up if you do a few
rotate/unrotate displays.
$ lsb_release -rd
Description: Ubuntu 18.04.1 LTS
Release: 18.04
$ apt-cache policy xserver-xorg-video-intel
xserver-xorg-video-intel:
Installed: 2:2.99.917+git20171229-1
Candidate: 2:2.99.917+git20171229-1
Version table:
*** 2:2.99.917+git20171229-1 500
500 http://us.archive.ubuntu.com/ubuntu bionic/main amd64 Packages
100 /var/lib/dpkg/status
$ xrandr
Screen 0: minimum 320 x 200, current 3120 x 1920, maximum 8192 x 8192
VGA-1 connected primary 1920x1080+1200+364 (normal left inverted right x axis y
axis) 0mm x 0mm
1024x768 60.00
800x600 60.32 56.25
848x480 60.00
640x480 59.94
1920x1080R 59.93*
HDMI-1 connected 1200x1920+0+0 left (normal left inverted right x axis y axis)
519mm x 324mm
1920x1200 59.95*+
1600x1200 60.00
1680x1050 59.88
1600x1000 60.01
1280x1024 85.02 75.02 60.02
1280x960 60.00
1152x864 75.00
1152x720 59.97
1024x768 75.03 60.00
832x624 74.55
800x600 75.00 60.32
640x480 75.00 59.94
720x400 70.08
DP-1 disconnected (normal left inverted right x axis y axis)
** Affects: xserver-xorg-video-intel (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1808626
Title:
Triple buffer flickering and weird display updating
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