[ltp] Re: Unstable Radeon output at 1920x1200

[Shem Multinymous]

On Mon, Mar 24, 2008 at 3:01 PM, Shem Multinymous <multinymous@gmail.com> wrote:
>  I have a problem driving LCD monitors at 1920x1200 via DVI on my T43
>  with Radeon X300. The image shows up, but is unstable: at erratic
>  times but generally once per 20-60 seconds, I get two disruptive
>  effects: the image disappears for a couple of seconds, or there is a
>  momentary image tearing effect. Basically, it looks like the monitor
>  is temporarily losing sync with the DVI signal. This occurs with 3
>  different LCD monitors and 3 different DVI cables.
>  Now, I know 1920x1200 24bpp is pushing the limit of DVI, but here's
>  the thing: when dual-booting into Windows, the display is rock-solid
>  at 1920x1200 24bpp DVI, using exactly the same hardware.

Update:

I was able to get a stable 1920x1200 on DVI by forcing a custom
modeline with a slightly lower pixel clock:
	Modeline  "1920x1200-dvi"  150.0   1920 1940 2007 2027   1200 1201
1204 1233   +hsync -vsync
For reference, Xorg's EDID default for this monitor is as follows:
	Modeline  "1920x1200"      154.0   1920 1968 2000 2080   1200 1203
1209 1235   +hsync -vsync

Still no idea why it works by default under Windows.

  Shem