# Xorg, radeon and dual-link dvi not working.



## ShruggingAtlas (Jun 16, 2010)

I have a core2 duo machine running 9-current with a Radeon HD4770 graphics card. I also have two monitors one 22" Samsung @ 1680x1050 and one 30" HP @ 2560x1600.

If I hook the machine up to the Samsung monitor everything works, including direct rendering. However, if I hook up the HP monitor all I get is rolling lines of brown, blue and yellow. This behavior occurs on both vesa, radeon and radeonhd drivers, even when setting Modes "1280x800" in the screen section.

With the HP monitor the computer remains responsive, and I can leave X and return to the console without problems. According to the Xorg log, the graphics card has recognized the details of the screen, including resolution, refresh rates and panel size. Still the only significant difference between the monitors I can think of is the need for dual-link dvi on the HP monitor (which I am using!).

So, at long last, my question to the forum is this: Does anyone know some xorg.conf kung-fu, which could allow me to use the HP monitor?

Thanks for reading,
Martin


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## wblock@ (Jun 16, 2010)

There's dual-link DVI-D and DVI-I, and maybe the HP monitor wants other than what your cable provides?

http://en.wikipedia.org/wiki/Digital_Visual_Interface


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## ShruggingAtlas (Jun 16, 2010)

wblock said:
			
		

> There's dual-link DVI-D and DVI-I, and maybe the HP monitor wants other than what your cable provides?



Thank you for responding, wblock. I should have stated that the setup works in Windows and in Linux (Fedora 13).

Martin


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## adamk (Jun 16, 2010)

You may want to check out the #radeon channel on freenode.  F13 is certainly using KMS by default, and FreeBSD is using UMS (because KMS is not available).  It's possible, I guess, that dual-link DVI is only available via KMS, but the folks on #radeon could let you know if that's the case.

Adam


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## wblock@ (Jun 16, 2010)

ShruggingAtlas said:
			
		

> Thank you for responding, wblock. I should have stated that the setup works in Windows and in Linux (Fedora 13).



Comparing the xorg.conf in Linux and FreeBSD might be useful, likewise with Xorg.0.log.


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## wblock@ (Jun 16, 2010)

adamk said:
			
		

> You may want to check out the #radeon channel on freenode.  F13 is certainly using KMS by default, and FreeBSD is using UMS (because KMS is not available).  It's possible, I guess, that dual-link DVI is only available via KMS, but the folks on #radeon could let you know if that's the case.



My HP monitor claimed to need dual-link, and it works.  L2335, 1920x1200, with dual link DVI-I cable.


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## joag (Dec 2, 2010)

*Dual Monitor - Unix (FreeBSD - Linux Slackware)*

This post is a bit old but in any case this is how I've managed to get things in a working state:

http://www.nixheiser.org/DualMonitor


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