video equipment still forcing my laptop to a lower res, argh

Marko Vojinovic vvmarko at panet.co.yu
Tue Sep 9 23:33:40 UTC 2008


On Tuesday 09 September 2008 13:02, Ed Greshko wrote:
> Robert P. J. Day wrote:
> > Quoting Ed Greshko <Ed.Greshko at greshko.com>:
> >> Robert P. J. Day wrote:
> >>> is there any way to de-activate that checking within X?  from what
> >>> you've
> >>> written, i'm assuming that the X server sees what's happening, and
> >>> consequently scales back on the resolution as a result.  is there an
> >>> option >> to tell X to simply ignore that and go with full WUXGA no
> >>> matter what?
[snip]
> >   um ... ok.  i have no idea how much of that is important since
> > the decision to go with 1152x864 seems to have been made already.
> > in any event, i'm open to suggestions.  and i'm still unclear on
> > what is making the decisions above.  the RADEON video chip itself?
> > based on what?
>
> Yes, the chip itself is making the decision itself.  Better said, it is
> the chip manufacture.  As I said earlier the chip and the output drivers
> (HW) are only capable to drive at the lower resolution on the external
> interface and the decision has been made to downgrade the internal
> interface to match.

After reading through the thread, may I suggest playing around with xrandr? 
You would typpically have three video devices on a laptop --- LVDS (the 
laptop display), VGA (the external display) and TV (the s-video output, if 
present).

Given more than one display present simultaneously on the system, there are 
two distinct ways of dealing with them:

(1) have all devices display *the same* picture --- in this case they are 
"cloned", and must all have the same resolution; this is chosen to be the 
lowest resolution common to all devices

(2) have each device display *its own* picture --- in this case each display 
has its own resolution, colors etc, and you can setup their mutual geometry; 
for example, configure the lvds to be "on the left of" vga, so dragging a 
window from lvds to its right edge moves it over to vga, etc.

To me it seems that you have situation (1) autoconfigured, while you would 
prefer (2). This is achieved by a suitable xrandr command, hopefully without 
any manual intervention in xorg.conf. It works until a reboot, until another 
xrandr command changes things, or until video devices change states, ie. get 
(un)plugged.

It has been some time since I configured two (and even three) displays 
simultaneously, but it should go along the lines of

xrandr --output LVDS --mode 1600x1200 --left-of VGA --output VGA  --mode 
800x600 --output TV --mode 640x480 --below LVDS

or something like that. [CAVEAT --- don't just copy-paste the above into a 
terminal, I wrote it off the top of my head... :-) ]

There are possible limitations with the total memory buffer which stores all 
displays, so you may need to arrange the geometry in the suitable way that 
fits inside the buffer, and so on... But it is all basically arranged via a 
single xrandr command like the above. You just need to give it appropriate 
arguments that suit you.

man xrandr, google :-)

HTH, :-)
Marko




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