https://bugs.freedesktop.org/show_bug.cgi?id=109298
--- Comment #6 from Alex Deucher alexdeucher@gmail.com --- (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.