Copied from launchpad.
After the screen locks I am unable to log back in because the screen with the login prompt is black, and the screen on my laptop just shows the Ubuntu logo.
Furthermore, if I then unplug the external monitor (in an attempt to force the log in option to be displayed on the laptop) the laptop screen then goes black and I can't do anything at all.
I can't reproduce this if I select "lock screen" from the UI, but it happens reliably if it locks due to inactivity.
- I am running a fresh install of 14.04
- I have it set to lock after 5 min of inactivity, and require login after lock
- I have an external monitor, configured to be on the left side of the laptop screen
Created attachment 101671 [details]
dmesg with WARN_ON's triggering
I can't reproduce it on my desktop. i will try it on a laptop.
One of the strange things about this bug is the excessive amount of times the following message appears:
[drm:drm_dp_i2c_do_msg] native defer
If you have the available resources, can you reproduce this bug with a different monitor and/or a different DP cable?
Our QA couldn't reproduce the issue here, Paulo couldn't reproduce the issue as well. I tried with IVB, eDP+HDMI and couldn't reproduce.
Then I went to our lab and got a SNB with LVDS and DP, installed a fresh 14.04, configured the external monitor to the left side and waited 5 minutes and also couldn't reproduce the issue. after 5 minutes it is lock and black and after I move the mouse everything just light up and I can normally log in.
On launchpad bugzillas I've seem people reporting the issue with non intel gpu.
or with hibrid using fglrx.
Please provide more info here. Can you double check if this happens even without hibrid and without the fglrx driver and provide the logs?
Link training fails -> black screen. Everything else is a red herring and are minor irrelevant issues.
(In reply to comment #0)
> Copied from launchpad.
What's the launchpad bug?
(In reply to comment #6)
> (In reply to comment #0)
> > Copied from launchpad.
> What's the launchpad bug?
Sorry, saw that now in the see also.
Any idea if an adapter was used? One reporter at launchpad says the problem is not present after switching from VGA to HDMI:
I guess this one is either fixed or dead.