Multiple problems with multiple monitors

Basil Mohamed Gohar basilgohar at
Mon Oct 13 14:23:16 UTC 2014


I've searched for bugs related to the specific problems I've been
having, and I've not been able to find anything that describes what I'm

I have an HP EliteBook 840 that also comes with an UltraDock, to which
I've plugged-in two external monitors and I use in conjunction with the
built-in laptop display. 

Issue #1: I use LUKS to encrypt my disk, and when I first start up the
computer, after choosing the kernel to boot into in GRUB, the GUI prompt
for the LUKS passphrase shows-up on the middle monitor, not the laptop's
built-in display. I don't mind this when I have multiple monitors
plugged-in, but when I boot-up without the external monitors, such as
when I'm unplugged from the UltraDock, I now get NO GUI prompt for the
LUKS passphrase. I can enter it, and I can see a text prompt if I hit
ESC. I suspect its attempting to display on the now phantom, unplugged
monitor. Note, it was never plugged-in during this cycle. The problem
is, I don't even know what's instructing LUKS or the GUI prompt to
display on any monitor, so I don't know where to go to debug this. 

Issue #2: When I undock my laptop while logged-in, Gnome Shell just
crashes. When I redock after the laptop has been started when
unconnected, one of the two external monitors start-up (the one
connected by VGA), but not the one connected by a DisplayPort
connection. And, recently (but not when I first started using this
laptop with the dock, which was about a month ago), now when I start-up
with the laptop docked and both external monitors connected, both
external monitors will be active, but the built-in display will show
nothing. Gnome Shell reports the built-in display is active, but will
not display anything unless I deactivate it and reactivate it via the
settings "Displays" utility. 

Issue #3: The monitor connected via DisplayPort display significant
tearing and delay on the upper-right half of the screen in the form of a
triangle taking-up half of the screen. Reading about displayport and
tearing issues, I guess the idea that these were resolved in the past. I
don't know if this is the same or something different. 

I don't mean to use devel as a bug reporting venue, but I think these
issues are either related or I just don't know how to address them to
make significant progress to fixing them. Any guidance is more than
welcome. Thanks! 

Libre Video
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