[Nouveau] 640x480 does not fill screen

[Dan Espen]

I've been using the NVidia drivers and recently managed to
get Nouveau working.  Well almost working.

Running the command:

xrandr -s 640x480

results in a desktop that spans the monitor but leaves black bands of
about a third of the screen on the top and bottom.
This results in an unreadable display playing games like Lbrickbuster2.
I'd like the display to fill the screen.

To confirm that this is a Nouveau issue, I switched back to NVidia
where 640x480 looks fine.

I'm using Fedora 29 (xorg-x11-drv-nouveau.x86_64 1:1.0.15-6.fc29),
NVidia-390 drivers, GeForce GTX 1050 Ti, and a DELL S2817Q.

-- 
Dan Espen