Cannot restore HDMI display after regular TV session

[Bengt Nilsson]

I use my system connected to a TV screen via HDMI. The TV screen is also used as a regular TV, input selected to be either HDMI or "antenna". After upgrading to 14.04 LTS, after a while of watching regular TV and going back to HDMI display, the TV reports "No signal". I try to revive by moving the mouse or press the keyboard, but nothing happens. I try to reconnect the HDMI cable, but no change. The keyboard and mouse are wireless with a USB reciever/transmitter from Logitech. The only way to restore operation is by forced power recycling, or connect remotely via ssh and do "reboot".
I have tried to set the screensaver and power manager so that the computer never idles, but there is no improvement.

I have had some trouble with the NVIDIA driver, the HDMI sound configuration is not stable. HDMI sound units come and go between boots. Maybe it is connected.

Nothing of this happened in the previous release, 13.04LTS.
The desktop display was readily available after setting the HDMI input selector on the TV after watching regular channels.

bnilsson@HTPC:~$ lsb_release -rd
Description: Ubuntu 14.04 LTS
Release: 14.04

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.2
ProcVersionSignature: Ubuntu 3.13.0-24.46-lowlatency 3.13.9
Uname: Linux 3.13.0-24-lowlatency x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: XFCE
Date: Sun Apr 27 22:50:58 2014
InstallationDate: Installed on 2013-08-24 (246 days ago)
InstallationMedia: Ubuntu-Studio 13.04 "Raring Ringtail" - Release amd64 (20130424)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
Symptom: dist-upgrade
UpgradeStatus: Upgraded to trusty on 2014-04-18 (9 days ago)
VarLogDistupgradeTermlog:

[Bengt Nilsson (bnilsson11)]

I realize that the tagging is incorrect, nothing is wrong with the release upgrader utility as such.
My point is that the bug is related to the new 14.04LTS distribution, which is not the same thing.
Please change it to something more suitable, I am not sure what it should be.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Mike O'Driscoll (modriscoll)]

I'm seeing same results as Bengt, I've attached my duplicate bug to this ticket.

[Bengt Nilsson (bnilsson11)]

I have found that a workaround is to press Ctrl-Alt-F1 for a terminal login, login as root and do:

service lightdm restart

This will invoke the graphical login screen, and I can log in as usual.

[Mike O'Driscoll (modriscoll)]

The workaround from the following bug fixed the issue for me:
https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-331/+bug/1308105

Recommend making this a duplicate.