xserver-xorg-ati: How do I force modeline ?

[Toan]

Hi

I don't know how to force a modeline for my HDTV. I hope someone can help me.

I have a Kubuntu 10.04, xorg-edger PPA latest packages, ATI Xpress
X1250 built-in
graphic chip. For whatever the reasons, the default 1280x720 mode used by the
the ati driver is wrong. The TV goes black when I select "1280x720" mode.

According to the xorg.0.log (attached), there are 2 "1280x720" modes available
(with same names for some weird reasons) :

[    21.523] (II) RADEON(0): Modeline "1280x720"x60.0   74.44  1280
1336 1472 1664  720 721 724 746 -hsync +vsync (44.7 kHz)
[    21.523] (II) RADEON(0): Modeline "1280x720"x60.0   74.25  1280
1390 1430 1650  720 725 730 750 +hsync +vsync (45.0 kHz)

Somehow, xserver insists on using the first mode. I want to force it
to choose the
second one, but don't know how to. I'm sure that the second one works because
I typed the following

xrandr --newmode "720p" 74.25 1280 1390 1430 1650 720 725 730 750 +HSync +VSync
xrandr --addmode DVI-0 720p
xrandr --output DVI-0 --mode 720p

and it works!.

Anyhelp would be greatly appreciated since I'm fighting this for
several days already
and nearly gaving up. 1080p works but XBMC is noticeably slow at that
resolution.
XBMC is much smoother at 1024x768 so I'm trying to force 720p
as my default mode. xrandr doesn't work for OpenGL program.

Thanks

Toan
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