Problems with dell 2407wfp

[Roland Scheidegger]

André Næss wrote:
> Hi
> 
> Just got me a new 24" widescreen monitor, but I'm having some trouble
>  getting it to display properly.
> 
> I've got a Dell D610 laptop with the integrated 915GM graphics card. 
> So my first step was to use 915resolution. I patched mode 32 to be 
> 1920x1200 24bits/pixel, and then set to work on xorg.conf. After
> quite a bit of fiddling I found a modeline that "works".
> 
> Modeline        "1920x1200" 154.128 1920 1968 2000 2080 1200 1203
> 1209 1235 +hsync -vsync
> 
> By "works" I mean I actually get a picture. The strange thing is 
> however that the monitor info screen says that it's running 
> 1600x1200 at 57Hz, while the actual desktop size is 1920x1200, meaning 
> 320 pixels on the far right are simply lost, and the image quality is
>  pretty lousy too.
> 
> I've tried using the modeline generator to find a suitable modeline, 
> but the result requires a pixel clock of something like 200+. The 
> monitor only handles 170. Looking at the documentation 
> (http://support.dell.com/support/edocs/monitors/2407WFP/en/about.htm#Specifications)
> 
> 
> you can see that the pixel clock keeps rising for the various 
> resolutions, then suddenly falls for the 1920x1200 resolution. Seems 
> odd to me, although I really don't understand what the pixel clock 
> really is.
Basically horizontal pixels * vertical pixels * refresh rate, but you'd
need to include the blanking intervals (both vertically and 
horizontally) too. The reason the pixel clock for the listed vesa 
1920x1200 mode is lower is because this mode uses reduced blanking 
(otherwise it would exceed the limit of single-link dvi), tft's don't 
really require blanking as analog monitors did (you certainly could use 
lower resolution modes with reduced blanking too).
As for why it doesn't work, I think there were similar reports some time 
ago, you might have more luck with the git modesetting branch of the 
intel ddx driver or at least just a newer version of the driver.

Roland