Radeon X300, dual head [SOLVED]

Hans J. Koch hjk at linutronix.de
Sat Nov 22 12:08:58 PST 2008

On Sat, Nov 22, 2008 at 01:22:58PM -0500, Alex Deucher wrote:
> On Fri, Nov 21, 2008 at 5:50 PM, Hans J. Koch <hjk at linutronix.de> wrote:
> > Hi,
> > I used to have a working system with a Radeon X300 (RV370) card and two
> > monitors 1680x1050 each. I used an ancient xorg version (something like
> > 6.8, can't recall) and had a MergedFB+Xinerama configuration. Worked well
> > for me.
> >
> > A few days ago I dist-upgraded my Debian sid which brought me version
> > 7.3 of xserver-xorg. Since that I'm trying to get my dual head setup
> > working again...
> >
> > I understand that MergedFB has been replaced by RandR 1.2 extensions.
> > Sounds like a good concept to me, but unfortunately it doesn't work here.
> >
> > X correctly detects my hardware, but no matter what I do, I always have
> > the same output on DVI-0 and VGA-0. I googled around and found a lot of
> > pages describing how to setup xorg.conf, and I think it's OK.
> >
> > Question: Is this supposed to work or a known problem? What do I have
> > to do to get a working dual head setup again?
> yes it should work.  you may need to add a virtual line to your config
> to reserve enough framebuffer space for your config.  This page gives
> a pretty good overview of how to configure things with xrandr:
> http://wiki.debian.org/XStrikeForce/HowToRandR12
> One problem that comes up from time to time is that the xserver will
> clone the outputs (drive both monitors with the same display
> controller rather than with independent display controllers).  The
> xrandr utility doesn't seem to be smart enough to grab a new crtc when
> you select multi-head, so you sometimes have to specify the crtc.  run
> xrandr --verbose to see how the topology is configured.
> You can use this set of commands to specify a crtc:
> xrandr --output VGA-0 --off
> xrandr --output VGA-0 --crtc 1 --mode 1680x1050
> xrandr --output VGA-0 --right-of DVI-0

Great, that does the trick. You made my day. It was quite boring with one
of my two monitors turned off ;-)

Thanks a lot,

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