[ltp] Help Please - MergedFB with xorg radeon driver has bad vertical resolution on second head

[Alex Deucher]

On Tue, 14 Dec 2004 20:54:37 -0500, morpheus <morpheus@post.harvard.edu> wrote:
> I know I rambled on in my last post, but I have two problems remaining
> when trying to use the MergedFB option of the xorg radeon driver for
> dual-head layout on my T42p.
> 
> 1. I cannot get any output from the DVI on my port replicator.
> Even with Option "MonitorLayout" "LVDS, TMDS" in the "Device" section I
> can only get output on the RGB connector, not the DVI connector.  Even
> with this setting, I get output on the RGB.
> 

the driver doesn't suppor this just yet.  the problem is there are
certain assumptions made about which crtc drives which output.  As far
as digital outputs are concerned, the driver always assumes crtc1 will
be LVDS (LCD) or internal TMDS (DVI) and crtc2 will be external TMDS. 
The output handling needs to be separated from the crtc handling;
theoritically either crtc can drive any output.  In your case crtc1
should be driving LVDS and crtc2 shoul be driving internal TMDS,
however the driver can only handle LVDS and external TMDS at the same
time (theoretically you could also have crtc2 drive LVDS and crtc1
could drive internal TMDS, you might want to do this if you wanted to
use RMX on the DVI port since RMX is only available on crtc1).  For a
more detailed discussion of this check out my response on yesterday's
xorg ML archives.  It's on my todo list, but I don't know when I'll
have time to get to it.  Patches welcome!

> 2. The vertical resolution on the second head is 176 pixels too high.  I
> have the first MetaModes set to "1600x1200-1280x1024", and the laptop
> internal LCD is at 1600x1200, but the external display is at 1280x1200.
> (I checked the dimensions with kruler, an awesome but little-known
> utility in KDE, great for graphic designers.)  If I move the mouse off
> the top or bottom, the screen scrolls to see the whole thing.
> 

This is a limitation of mergedfb.  think of mergedfb as being one big
framebuffer with two windows looking into it.  since the framebuffer
has be rectangular, one or both of the frames must scroll so that you
can access the whole thing otherwise windows could get stranded in an
unreachable part of the framebuffer.  If you want two framebuffers of
different sizes stitched together, you'll have to use xinerama style
multi-head (two screen, device, monitor sections etc.).

hope this helps,

Alex

> I'd be a very happy person if someone could help me with these.
> 
> -m
> 
> FYI, my xorg.conf is below:
>