External monitor resolution problem (i810)

Gordan Krešić gordan.kresic at mobart.hr
Tue Nov 21 06:59:06 PST 2006


I've got HP laptop NC6400 with Intels' 945GM graphics controller and after
some time spending on Linux basics I've successfully setup everything, 
including DRI, DPMS, with "915resolution" I've got my laptops native 
1280x800 resolution, DDC is read corectly and DPI is correct (something 
above 100 DPI). Fonts are looking great.

Unfortunately I was lucky enough to got additional port replicator and
external LCD (Samsung SyncMaster 931BF, native 1280x1024) and there is where
my pain begun.

Simply put - I was not able to get proper resolution on my external screen 
when trying to switch (duplicate) my laptop's screen. Basically what I want 
is to switch my screen (via Fn+F4) to external screen (this part works 
correctly right now) and then to _change resolution_ to external screen's 
native resolution (which is greater than my laptops native - 1280x1024 vs 
1280x800).

 From logs (see attachments) I can see that external screen's DDE is read 
correctly, but xrandr does not offer me to change resolution. For things to 
be worse, if I boot with external screen connected, resolutions are picked 
from my internal screen but DisplaySize is picked from my external monitor 
which has greater physical dimensions which screw DPI settings.

Currently I'm working with forced 100 DPI ("-dpi 100" switch when
starting X) with non-fullscreen 1280x800 resolution on my external screen,
but I would be much happier with proper 1280x1024 on external screen ;)
External LCD is connected through DVI cable. My laptop is not always docked,
moreover it is sometimes booted on dock, and sometimes without it.
Restarting X everytime I dock/undock is less acceptable than non-native
resolution on external screen ;)

All informations that I found relevant are in attachments.

Currently I'm using i810_drv.so from 
http://www.fairlite.demon.co.uk/intel.html but I don't see any improvements
over Debians default version from testing branch.

X info is:

X Window System Version 7.1.1
Release Date: 12 May 2006
X Protocol Version 11, Revision 0, Release 7.1.1
Build Operating System: UNKNOWN
Current Operating System: Linux mata 2.6.19-rc5-gkresic #4 SMP Sun Nov 12 
14:52:09 CET 2006 i686
Build Date: 07 July 2006

At first I believed that xrandr extension does not provide ways of defining 
another resolutions and changing display size after X started, but I saw it 
working on my colegue's laptop (same machine, but with ATI graphics and fglrx).

Option with defining another screen (:0.1 for example) is not an option 
because external monitor is not always connected and AFAIK switching 
applications between displays is not possible.

I played with different options for the past few weeks and only time that I 
got external's monitor native resolution available was with option

Option          "MonitorLayout"         "LFP,DFP"

but then I was unable to start X when external monitor was not connected.


Tnx in advance,

	-gkresic.

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