Comment 22 for bug 255678

Got a good hint in #440590:
The modules must be reloaded after boottime to work correctly:

modprobe -r gspca-sunplus
modprobe gscpa-sunplus

That does the trick for me! A /dev/videoX is created, accessable and full functioning!
I hadn't success putting these lines in rc.local - it won't be executed. Still have to figure out, why. But if I execute the two lines by hand after every boot, I have my webcam back, again!