Lenovo G555 video issue

[Understudy]

Hi,

I have a Lenovo G555 with a M880G [Mobility Radeon HD 4200] video card. 
After the upgrade of the xorg port to 7.5 the screen became wavy and 
basically not usable. I am trying to find the driver (xf86-video) for it 
so I can do a portdowngrade. The efforts at port downgrade on the xorg 
meta port did not work. The question is there are several xf86 video 
drives with ATI or Radeon which one is being used?

Sincerely,
Brendhan