fix for geforce 420/440 go black screen with 9639 driver

[zero79]

owners of geforce 420 and 440 go cards (and perhaps others) are getting a black screen with the 9639 legacy driver. the problem is that the driver thinks it is supposed to output to the vga port by default even though those cards are laptop cards and should be outputting to the lcd.

there is a pretty simple fix. just add

Option "UseDisplayDevice" "DFP"

to the Screen section of xorg.conf to force the card to output to the lcd.

note that this problem does not happen with the 7185 legacy driver. so something broke somewhere between those releases.

nvidia, can you update the 9639 driver so that the 420 and 440 go cards output to the lcd by default?

thank you very much.