First of all, there are two different drivers for the DS4 - hid_sony and hid_playstation. hid_playstation is a relatively new one, developed by Sony. hid_sony is an older one which had been reverse engineered years earlier. There was a good stretch of time where hid_sony worked perfectly for me, but now I seem to need hid_playstation. On Gentoo, since about a year ago, I have had to manually enable hid_playstation in the kernel menuconfig (which required enabling an additional LED driver first) and use it instead of hid_sony to get my DS4 working. Otherwise I had problems where it would work some nights, not work at all others, or just the trackpad would work for some reason.