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

[Alex Deucher]

On Wed, Jun 2, 2010 at 9:53 AM, Toan <nguyenthetoan at gmail.com> wrote:
> 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!.
>

Add that modeline and a preferred mode directive to the monitor
section in your xorg.conf.  Set the Identifier of the monitor section
to DVI-0 so that that monitor section will be associated with the
DVI-0 port on your card.  See section III.5 of this page:
http://wiki.debian.org/XStrikeForce/HowToRandR12

Alex

> 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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>