pulsar Thank you for your findings! I think there is no special treatment needed to make the build work on both S905 and S905X after your kernel config changes. I have built a new build with my 4K fixes included, I'd be great if you can try if it works:
s905x-test1
If you install above test version, you should still be able to boot into recovery without SD card inserted or into LE from SD card. Try SD version first to confirm if it works.
So I tried with your version kszaq: didn't work on my Mini M8s II (2GB/8GB - S905X)
pulsar yours works.
Very smooth playback of 23.976p files
EDIT: Just shutdown and then power on doesn't work.
So i've to cut power and plug it in again.