External VGA blinks every 7 seconds with both outputs enabled

Bug #287128 reported by Benoit St-André
18
This bug affects 2 people
Affects Status Importance Assigned to Milestone
xserver-xorg-video-intel (Ubuntu)
Triaged
Medium
Unassigned

Bug Description

Thinkpad X41 laptop, with intel 915GM/GMS/910GML, with Intrepid Kubuntu up to date at the moment I'm posting this.

Using an external VGA screen with LVDS at the same time causes the VGA screen to blink / flicker every 6-8 seconds (just gets black completely, and gets back less then a second later).

I'm attaching my Xorg.0.log , but the three following lines always appear when the screen flashes:
(II) intel(0): EDID vendor "ACR", prod id 9
(II) intel(0): I2C device "LVDSDDC_C:ddc2" registered at address 0xA0.
(II) intel(0): I2C device "LVDSDDC_C:ddc2" removed.

For example,
/usr/bin/xrandr --output VGA --auto --left-of LVDS
gives me the twin view setup (with just a line Virtual added in my xorg.conf, although it did do that with the pristine xorg automatically built up by dpkg). It does the same with --same-as options.

It does not flicker when using only VGA, or only using LVDS (using xrandr --output VGA --auto --output LVDS --off or the other way around)

The bug may seem similar to other bugs (like #275152), but the main issue here is that it is a regression, as this kind of setup was perfectly working under Hardy before the upgrade.

I upgraded to Intrepid since October 14th , and it's been doing this since (even with the multiple xorg / video-intel) upgrades.

A workaround (not a solution ! this is not a normal behaviour) is to stop "Detecting RANDR (monitor) changes" in KDE settings like described in bug #278471

After doing that, screen stops blinking , whatever the setup is. I post the bug in xserver-xorg-video-intel , not sure if it is really a hardware bug or what.

Willing to test whatever needed to solve the issue for a standard setup that will work out-of-the-box for those poor Kubuntu Intrepid people that will have my kind of video hardware (that seem to be common).

Revision history for this message
Benoit St-André (benoit-st-andre) wrote :
Revision history for this message
Benoit St-André (benoit-st-andre) wrote :
Revision history for this message
Benoit St-André (benoit-st-andre) wrote :
Changed in xserver-xorg-video-intel:
importance: Undecided → Medium
status: New → Triaged
Revision history for this message
Jakob Petsovits (jpetso) wrote :

Turning off the KRandR service also gets rid of video playback stutter and mouse jumps, as reported here: https://bugs.launchpad.net/ubuntu/+source/kubuntu-meta/+bug/296481

Geir Ove Myhr (gomyhr)
tags: added: dual-head
removed: external
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