Comment 7 for bug 538377

Forwarding this bug from Ubuntu reporter Daniel Newman:
http://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/538377

[Problem]
Intermittently with HDMI the display turns off and the monitor reports no HDMI output.

[Workaround]
When this occurs, issue the following commands:

xrandr -d :0 --output DVI-0 --mode 1024x768

which makes the display visible again, in the lower resolution, then

xrandr -d :0 --output DVI-0 --mode 1920x1200

which restores the original display. Things then function normally until the next random HDMI output failure.

[Original Description]
1) lsb_release -rd
Description: Ubuntu lucid (development branch)
Release: 10.04

2) apt-cache policy xserver-xorg-video-radeon
xserver-xorg-video-radeon:
  Installed: 1:6.12.191+git20100306.e7b41f8c-0ubuntu0sarvatt
  Candidate: 1:6.12.191+git20100306.e7b41f8c-0ubuntu0sarvatt
  Version table:
 *** 1:6.12.191+git20100306.e7b41f8c-0ubuntu0sarvatt 0
        500 http://ppa.launchpad.net lucid/main Packages
        100 /var/lib/dpkg/status
     1:6.12.191-1ubuntu2 0
        500 http://archive.ubuntu.com lucid/main Packages

3) The HD3450 DVI-HDMI output is connected by HDMI cable to an ASUS MK241H monitor. It should provide a 1920x1200 display + audio via the monitor. When it does so, xrandr reports:

xrandr -q
Screen 0: minimum 320 x 200, current 1920 x 1200, maximum 8192 x 8192
DIN disconnected (normal left inverted right x axis y axis)
VGA-0 disconnected (normal left inverted right x axis y axis)
DVI-0 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200 60.0*+
   1920x1080 60.0
   1600x1200 60.0
   1680x1050 60.0
   1600x1024 60.2
   1400x1050 70.0 60.0 60.0
   1280x1024 75.0 60.0
   1440x900 75.0 59.9
   1280x960 60.0
   1360x765 59.8
   1360x768 60.0 59.8
   1280x800 74.9 59.8
   1152x864 75.0 75.0 70.0 60.0
   1280x768 74.9 59.9
   1280x720 60.0
   1024x768 75.1 75.0 70.1 60.0
   832x624 74.6
   800x600 72.2 75.0 60.3 56.2
   720x576 50.0
   848x480 60.0
   720x480 59.9
   640x480 75.0 72.8 72.8 72.8 75.0 60.0 59.9 59.9
   720x400 70.1

4) The display generally starts fine, but intermittently, after apparently random times and with random programs running, the display turns off and the monitor reports no HDMI output. Logging in from another machine, everything appears to be normal and xrandr reports the same as above. However, there is no HDMI output to the monitor. This can be fixed by xrandr, using first:

xrandr -d :0 --output DVI-0 --mode 1024x768

which makes the display visible again, in the lower resolution, then

xrandr -d :0 --output DVI-0 --mode 1920x1200

which restores the original display. Things then function normally until the next random HDMI output failure.

Previously, under karmic, I used the closed source "fglrx" driver on the system. It functioned correctly, without any drop-outs.

Having mplayer running continuously but paused seems to prevent the HDMI output turning off. Maybe this is some power management issue, where
having mplayer running prevents the HDMI output getting into some low
power state from which it cannot return.