No Linux kernel has full 4k HDR support. The current 3.14 kernel predates HDR and has been hacked by Amlogic and various community groups to have some resemblance of HDR support, but the test cases it was coded for are limited and bits are missing. Folks over at CE lack the kernel development skills to architect and solve those problems which is why they've flip-flopped between kszaq, osmc and our older kernel in the hope they find something that works. We (LE) are not wasting our time on that quest because we know none of them work properly, and the 3.14 kernel is not really worth the effort. The situation on mainline kernels is also incomplete as HDR and other HDMI 2.0 elements are still being coded. The good (long-term) thing is that those feature are being actively worked upon, and unlike ye olde 3.14 kernel, the code is written properly.
Why don't you tell us a bit more about your contribution to LE and to the community? I would love to finally learn how can I feel useful without accomplishing nothing! Instead I spend hours trying to fix what is not working properly and sharing what I learn so can other go further than me.
Seriously, if you start spending all the effort that you waste on complaining about everything and everyone that is really just here for fun and to try to do something useful, in fixing LE problems, I'm sure that in a few days LE would be flawless.