Come on, it's surely not to difficult to "fix" the debian image.
You need to change the bootloader, u-boot, kernel, board.dtb and the kernel-modules.
Well, I have somewhat "updated" the debian-s500 original image:
Link to my shared folder
4."installed" binary GPU libs
5.installed glmark2-es2, mesa-utils
6.image is updated to 2016.06.02 and can display real 1080p
7.glmark2-es2 benchmark = 193, glmark2 = 143
Pay attention when you install or update packages that it can overwrite the binary GPU driver libs.
I had to rename some "old" libraries to make all things work ldconfig was not enough.
it would be greatly appreciated if actions provides some "real" installable driver and not a bunch of crappy binary libs!