I have reluctantly come to the conclusion that these displays really require a receiver with at least two HDMI outputs to function at their full potential.I'll likely buy an HDMI switcher in the future, though only if they sell one that is 4k/60hz 4:4:4 capable. The last switcher I had worked very well and didn't add any perceivable lag.
I use HDMI 5 for PC because I use my PC every day and play most of my games on PC. The PS4 is only turned on once in awhile. If it were opposite, I'd use PS4 on HDMI 5 instead.
I have a Yamaha V799 that is relatively inexpensive and it has two HDMI outputs. I route my PS4 and my Computer through the output number 2 to the Display’s HDMI input 5 for all of my gaming needs. That also gives me 1080p @ 120 FPS for the computer games.
I route all regular Cable/Satellite video through the HDMI output 1 of the receiver into HDMI 1 of the P-series. That gives me the ability to use ARC and to use a completely separate profile in the P-series for TV programs. I typically reduce sharpness to about 13 on that input only.
Then my K8500 UHD Blu ray player luckily has two HDMI outputs. One goes into the receiver the other goes into HDMI 2 on the Display. That gives me the chance to use an entirely separate profile for the Blu rays as well. It also avoids the HDR and HDCP pass-through issues my receiver currently has.
Without the receiver I would have to make quite a few compromises. For as low as $500 it might be a good option for some people.