DVI output not visible on LCD with DVI, VGA output works -- (MergedFB on Ubuntu Edgy, Powerbook G4 ATI radeon 9600 M10)

Alex Deucher alexdeucher at gmail.com
Fri Jan 12 06:23:01 PST 2007

On 1/12/07, Martin Langhoff <martin.langhoff at gmail.com> wrote:
> On 1/6/07, Alex Deucher <alexdeucher at gmail.com> wrote:
> > I'll try and take a look this weekend.  I haven't updated my git tree
> > since before the holidays.  Can anyone else reproduce this?  Any
> > chance you could git bisect to find the change that causes the crash?
> Bisecting now. Hmmmm. Lead me to 452f0 , David Airlie's "radeon: bring
> over final set of changes...". Trying to revert it on top of master
> leads to several conflicts that I am not sure how to resolve, so I
> leave things there. This _may_ be due that this machine has no BIOS as
> such.
> Now, what brought me here is that I can't get one of my monitors to
> read DVI signal from this machine. And I've been figuring out a few
> more things in that aspect. (but still having trouble with it)
> All these tests are with 6.2 (and tested occasionally with 6.3 but it
> does exactly the same as 6.2 AFAICT). With master, the whole thing
> crashes, so no chance to test.
> With MonitorLayout set to "LVDS, TMDS" and some radeontool poking at
> - my work LCD likes the DVI signal (@1280x1024) and the VGA signal
> (over DVI->VGA)
> - my home LCD doesn't like the DVI signal(@1440x900), likes VGA (over DVI->VGA)
> The funny thing is, the log reports in BOTH cases the external monitor
> detected as Connector: VGA. DDC Type: VGA_DDC. So it must be sending
> out VGA+DVI signal, and for some reason my home monitor isn't liking
> the DVI signal.

Barring a connector table we make some guesses in the driver.  Also,
ati apple cards tend to wire up the DDC lines differently or provide

> Any suggestions? I will surely try master as soon as I can run it
> ;-)... and I have tried a bit with reduced blanking (I'll probably
> retry that now too).

reduced blanking may help. You might also experiment with some
slightly tweaked modelines.


> thanks!
> martin

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