25 More AMDGPU DC Patches, Mostly Focused On Raven DCN

While waiting on David Airlie to send in the AMDGPU DC pull request for Linux 4.15, additional AMDGPU DC material continues building up for what should in turn target Linux 4.16.

Besides AMDGPU DC fixes still allowed to head into Linux 4.15 if the merge goes through, there continues to be the flow of new AMDGPU display code patches flowing on the AMD mailing list.

The latest 25 patches posted today yield a "bunch of changes" to get frontend/backend programming right on DCN, more fixes for DCN, and minor code clean-ups.

DCN in this context is for current the DCN 1.0 Raven Ridge family of display engines. The just-launched Vega+Zen APUs feature a new display engine and that's what this DCN code is for, which is also under a separate Kconfig tunable from the rest of AMDGPU DC.

Given the continued code churn around DCN / Raven Ridge, it will be interesting to see if or how well Raven Ridge APU laptops fair on Linux 4.15 or if the display support for these newer laptops really won't get into shape until Linux 4.16. So far there's just the lone HP laptop out in retail channels as Raven Ridge based but more are expected soon. The main downside if the DCN/Raven support isn't properly baked for Linux 4.15 is that it will miss the out-of-the-box Ubuntu 18.04 LTS experience, albeit will later get in for 18.04.2 when it has the HWE backport from what will be Ubuntu 18.10. As soon as I find an interesting Raven Ridge laptop available, I plan to pick one up for testing and use as my next production system if all goes well, as there's been no word on review samples for Linux testing.

These latest AMDGPU DC patches can be found on amd-gfx.