Problem setting up dualhead with notebook and xrandr

[kzot at gmx.net]

Hi,

I switched over from radeohd to radeon/ati for testing and encountered two 
problems with dualhead setup and xrandr; maybe someone here can me help out a 
bit.

Setup is as follows: T60 Notebook in docking station (display "LVDS" and 
resolution 1400x1050) and two external displays via DVI (display "DVI-0" and 
resolution 1280x1024) and VGA (display "VGA-0" and resolution 1280x1024).

Goal is to disable the notebook display and have a dualhead on the two 
external displays.

=1=
xrandr initially reports back as maximum resolution 1400x1400 (the biggest 
screen). For dualhead on the two external display (2560x1024) to small.

I have workarounded it by adding a subsection in my xorg.conf: 

Subsection "Display"
  Virtual 2560 2560
EndSubsection

Just wondering what is needed to autodetect this, because radeonhd set it 
correctly to this without needing the hint of a subsction?

=2=
Trying to enable the dualhead on the external displays fails.

I disabled the LVDS display via "xrandr --output LVDS --off" and tried to 
enable the external displays in dualhead mode "xrandr --output VGA-0 --left-of 
DVI-0". Which does not change anything.

After toying around a bit with "xrandr --output X --pos XxY" it seems that 
both VGA-0 and DVI-0 are modified together when changing a parameter of one, 
e.g. setting "xrandr --output DVI-0 --pos 100x0" moves both DVI-0 and VGA-0 
100 pixel right. 

What can be wrong here?


Versions are (Mandriva Cooker RPMs):
* x11-server-xorg-1.5.99.3-1.20081222
* x11-driver-video-ati-6.9.0

Thanks for any help.