So for about the last 7 months there has been a bug I falsely believed had something to do with my work laptop, the Thinkpad X60. The setup is simple but elegant; laptop sits on its docking station and a 24 inch Dell 2407WFP handles my terms. I suspected that the BIOS update which allowed my X60 to reach higher resolutions when connected via external panel was reporting an incorrect video mode to the monitor. Turns out, the sync polarity detected by Intel’s open and free driver is incorrect. So this means that the monitor is reporting the incorrect polarity which is why I would experience a nasty refresh shake.
That answered, it work’s fine with Windows(tm) so i’m wondering if the new Dell Linux team (the one that really sells Linux now) is making sure the fixes that go out for Windows(tm) are also making their way into the hands of us Opensource types. Maybe there was some obvious communication between Dell and Microsoft and/or whoever wrote the driver for Windows saw and fixed this issue themselves. We’ll probably never know.
Workaround
The work around for now is doing something like (this is for a 1920×1200 mode if at a lower resolution simply make sure +HSync -Vsync and NOT -HSync +Vsync):
- xrandr –newmode debug1 154.0 1920 1968 2000 2080 1200 1203 1209 1235 +HSync -Vsync
- xrandr –addmode VGA debug1
- xrandr –output VGA –mode debug1 –verbose –preferred
My latest git pull still doesn’t see this issue fixed. I’ll pull the exact patch and apply if I get sometime next week to see if it’s fixed.
All bug info here; by the way i’d like to thank Intel for the open driver!
