blank external DVI on Thinkpad T40

Gilad Arnold arnold at
Wed Feb 25 14:51:02 PST 2009

On Wed, Feb 25, 2009 at 05:25:14PM -0500, Alex Deucher wrote:
> DVI is usually much pickier about modes than VGA.  you might try the
> 59.9 mode on the DVI:
> xrandr --output DVI-0 --mode 1920x1200 --rate 59.9

I get the same result (i.e. no picture on the DVI) except that my
picture quality deteriorates even more on the VGA with 59.9  (for some
reason, changing the mode of the DVI-0 changes the mode of the VGA-0

> from the hardware's perspective they do the same thing: turn off the
> output and disable the crtc driving it.

Does xorg/driver rearrange the video memory layout when xrandr disables
a display with the --off switch, even though the monitor is still
connected?  I'm close to moron when it comes to video controllers and
being purely speculative, but I suspect that --off only shuts down the
signal/CRTC but retains and updates the video RAM allocated to the LVDS,
thus not helping to eliminate the problem (be it memory overflow,
bandwidth limitation, etc).

> I'll take a look and let you know.

Million thanks. This has been very frustrating, and your help is very


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