(In reply to tkdestroyer2+bugs-freedesktop from comment #2)
> (In reply to Michel Dänzer from comment #1)
> > Does not specifying the dpm parameter at all on the kernel command line or
> > anywhere else make a difference?
> 
> I just tested. DPM is required to prevent crashing, but DC is not.

4.18 and older used the old dpm implementation by default and setting to 1
selected the new one.  The new on is default in 4.19, so you no longer need to
specify dpm=1 as of 4.19.