ubuntu 15 on dell xps15

[robert]

Hi there,
I recently bought a dell xps15 laptop with a 4k monitor.
A very nice computer in deed..

However I do have some problems using it with ubuntu 15.04
- Sometimes it does not wake up from the sleep mode
- generally I am fighting with the high resolution.

The xps's little brother, the del xps 13 can be ordered with ubuntu 
14.04 LTS, and I read that dell worked with canonical to adapt the 
necessary kernel modules.

Now I wonder, are there adapted drivers for ubuntu 15 somewher?
I did not find anything.

thanks
robert