[ltp] Display Port / Intel graphics adapter users

Alex Deucher linux-thinkpad@linux-thinkpad.org
Tue, 1 Feb 2011 12:53:46 -0500

On Tue, Feb 1, 2011 at 12:39 PM, Damon Lynch <damonlynch@gmail.com> wrote:
> Hi,
> I presume other Thinkpad users using the internal Intel video adapter
> connected to an external monitor via Display Port have run into the same bug
> as me - that the external monitor never goes into an energy saving state
> when the laptop LCD is powered off. At least, this is what I find using
> Ubuntu. This is most unfortunate. An obvious workaround is to power off the
> monitor manually when leaving the desk. But when it is switched on again
> Gnome *always* reverts to a lowest-common-denominator mirrored display,
> despite not being in that mode previously. It's difficult to imagine that
> anyone actually wants to use their laptop with this display setup.
> If so, and you're interested in having it fixed, please see this bug report:
> https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/711093
> I imagine it would be helpful if users of Thinkpads other than a T400s could
> report if the same bug affects them too. This bug has been present in Ubuntu
> since at least the time of 10.04, and possibly before.

I think this may be a logic issue in gnome power manager (GPM) rather
than the driver.  If the following commands executed from a terminal
blank the displays properly:
sleep 5; xset dpms force off
then the driver is working correctly.  I have similar issues on fedora
on a w500 with AMD gaphics, so I suspect it's a GPM issue.


> Damon
> --
> http://www.damonlynch.net