This from one of the leading Linux Forums - Phoronix: https://www.phoronix.com/scan.php?page=news_item&px=AMDGPU-Fixes-Ahead-4.20&utm_source=quora&utm_medium=referral
Following several interesting and exciting feature pull requests for the next Linux kernel (to be released as either version 4.20 or 5.0), AMD developers have moved onto stabilizing this massive amount of new feature code.
The first "fixes" pull request was submitted today to DRM-Next focusing on stabilizing and fixing issues stemming from all this new code. As a reminder, that feature code ranges from AMD Picasso APU support along with Raven 2, a lot of Vega 20 enablement code including compute support, initial xGMI support, VCN dynamic power gating, DC display code enhancements, VCN JPEG engine support, Raven Ridge GFXOFF support, GPUVM virtual memory performance improvements, and a variety of other interesting work.
With this first batch of fixes for this next kernel, there are several display/DC fixes, endian fixes for Vega, Vega 20 PowerPlay fixes, Picasso/Raven/Raven2 PowerPlay fixes too, manual fan control mode switching fixes, and a variety of other fixes pertaining to the yet-to-be-released Vega 20, Raven 2, and Picasso hardware. It looks like by the time that hardware ships in the months ahead we'll see good Linux support in place! Now it's just a matter of when we begin to see Navi code published for AMDGPU and that may provide some signs of when we could potentially see Radeon Navi graphics cards releasing in 2019... Assuming once again the AMD developers are able to deliver the open-source driver support ahead of release for these highly anticipated discrete GPUs.
There is also a bit of a new "feature" with this pull request: enablement code for a new Vega 20 called "MGPU fan boost." At first I was thinking that MGPU may have been for "mobile" GPUs (so far all indications are V20 is just for discrete cards) but instead it's for multi-GPUs. This MGPU fan boost capability is about boosting the fan speed when there are at least two (Vega 20) discrete GPUs installed in the system. This fan boost is a feature of the hardware with its system management controller and just not some driver decision to up the fan speed. In going through the code it does appear Vega 20 is indeed the first AMD graphics card supporting this multi-GPU fan boosting functionality.
Vega 20 is widely anticipated to be a workstation GPU with a focus on deep learning workloads. For those GPU compute workloads it's no surprise at all many will be running them in a multi-GPU configuration where the noise level is less of a concern than with enthusiasts/gamers and more pressing is ensuring peak performance with no thermal throttling.
The complete list of fixes for the AMDGPU Direct Rendering Manager driver can be found via this pull