Re: Flickering screen on a cinema display.
Charles Plessy wrote:
> Le Fri, Apr 27, 2007 at 10:22:21PM -0400, Wakko Warner a ?crit :
> > Yes, I had this with a radeon 9200 on a PC and a 1600x1200 LCD connected via
> > DVI (Did not occur with VGA). I had to tell xorg to ignore edid and I
> > modified each mode line's dot clock to the absolute lowest it would go (down
> > to 2 decimal places). I still had flickering at 1600x1200. I've since
> > replaced it with a Fire GL X1 card and the flicker is completely gone.
> >
> > It seems to be the fact there's not enough bandwidth on a single link DVI
> > cable. I didn't have a dual link to test with so I'm not sure if that helps
> > or not.
>
> As everything works OK on osX, I wonder what kind of black magick is
> used by Apple... My problem is that I can not ask for a new graphical
> card just because I can not install linux on my work computer: working
> with linux is more comfortable in some cases, but as anyway osX is
> required for many things (flash, MS office, ...) so I can not justify
> such spending :(
I'm not sure I would call this black magic. They just drive the monitor at
50hz instead of 60hz. I only replaced my video card for one that was better
and it had the added benefit of no flicker (with the same configuration as
the older one)
> How did you tell xorg to ignore "edid" ?
man radeon and look for "EDID". I'm not sure what video chip is in your
mac but the option should work for other drivers. The options go in the
section where the video card is defined.
You can also use xvidtune to show you your current modeline that you would
place in the monitor section of the xorg.conf. There is a warning, but if
all you're going to do is have it show that information, it won't do any
damage. You'll probably have to run that from the terminal since it shows
the modeline on the screen.
It shows this for mine at 1600x1200:
"1600x1200" 135.00 1600 1664 1856 2160 1200 1201 1204 1250
If want to lower the hz from 60 to 50, you'll have to lower the 2nd number
(this is the dot clock) until its as low as it'll go. It probably took me
10 minutes per resolution that I use to get all at 50hz.
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