[ltp] Re: Unstable Radeon output at 1920x1200

[Shem Multinymous]

Hi Alex,

On Mon, Mar 24, 2008 at 5:21 PM, Alex Deucher <alexdeucher@gmail.com> wrote:
> On Mon, Mar 24, 2008 at 4:24 PM, Alex Deucher <alexdeucher@gmail.com> wrote:
>  > 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.

>  >  >  Is this just a matter of getting Xorg to use a better modeline, or
>  >  >  something deeper such as misconfigured Radeon CRTC registers?

>  Sounds similar to bug 15175.  Does this patch help?
>  I suspect the monitor may prefer slightly different dividers for the
>  pll.  Even though they get to the same clock, some monitors seem to
>  prefer different dividers combinations.

No, I'm afraid the patch doesn't make a difference.

I'm sending the logs off-list.

  Shem