[ltp] Dual-head non-scrolling viewport

[John Locke]

Apologies to the list for the repeated posts... the last one I had sent
earlier, and must've been stuck in the moderation queue.

Thanks, Alex, for all your help on this. I've corrected the Hsync and my
expectations ;-) 


On Mon, 2005-02-21 at 12:40 +0100, Michael Hagemann wrote:
> Hi Bob,
> 
> 
> Bob Alexander wrote:
> > John,
> > sorry for disturbing directly but I am really LOST with one aspect of my 
> > X and I believe you are much much more experienced than me.
> > 
Well, I don't know about that. I do feel like I'm starting to get a
grasp on the config file, but my understanding is still limited...

> > If you have a few minutes I would like to know if you can come up with 
> > some ideas.
> > 
> > My X works very very well on my T40 panel (1400x1050).
> > 
> > The problem I have is that when I use an external projector to give 
> > lectures on how beautiful Linux is :) I cannot manage to see the full 
> > screen.

The one thing I notice in you xorg.conf file is this section:


> Section "Screen"
>         Identifier      "IBM T40 external Screen"
>         Device          "ATI Radeon Mobility 9000 M9 dac Device"
>         Monitor         "T40 external"
>         DefaultDepth    24
>         SubSection "Display"
>                 Depth           24
>                 Modes           "1280x1024"
>         EndSubSection
> EndSection

If I understand the way your file is set up, this is what is used for
your external display. And you only have one mode here: 1280x1024.
Because there's only one mode, you can't change the resolution of your
external projector.

Try adding a couple more modes:

 Modes           "1280x1024" "1024x768" "800x600"

> > 
> > Even if I resize the internal LCD to 1024x768 or even to 800x600, the 
> > external projector, connected to the side VGA connector, will miss the 
> > height of the GNOME panel from above and approx. 20% of the left side of 
> > what I see on the internal LCD.
> > 
That's because you only have multiple modes available for your laptop
display, not the external display.

> > Here are some data. Thank you for any help.
> > Bob
> > 
> > PS Asked before but maybe I am too stupid to ask the right question :(
> 
> I had the same problem before, and recently had some luck with a 
> different projector.  I played with "CRT2HSync" and "CRT2VRefresh" 
> options, which you also see in John's device section.  I set them to 
> relative low values (vrefresh 50Hz), and got a nice projected picture. 
> Now I only don't know whether the projector was better than the first 
> one, or whether this generally helps...  Would be nice if you could try 
> it on your projector.
> 

If I understand correctly, these directives are for the MergedFB mode,
which is what I was using. Your file I'm guessing does not use MergedFB,
because it has a separate screen and monitor defined. Mine does not--it
uses the same screen settings for both internal and external. That's
what MergedFB does--handles the second monitor in the driver, instead of
in X. So MergedFB gives you better performance, but normal Xinerama and
multiple screens gives you more flexibility. 

Cheers,
-- 
John Locke
"Open Source Solutions for Small Business Problems"
published by Charles River Media, June 2004
http://www.freelock.com