So I was digging the code around for the Vega 20 Branch and the Vega 12 (which is now upstreamed)
Vega 20 adds support for Zero Frame Buffer (which I dont know what it does), Emulation Mode, new Data Fabric.
However I wish the DKMS present in this branch would be mainstreamed, because we could use any Linux version or distro and load the Kernel Module without upgrading the distro or wait for a new release.
The code looks far from prime time, looks like a HW bring up driver.
On the Vega 12 side I saw
It has a new SMU MicroCode
It has 16 DPM levels compared to 8 of Vega 10
It has a simplified thermal management and no LED control unlike Vega 10
It still has fan rpm control, which might suggest it is also meant for desktop
Funny thing is getting rid of the complicated Fan and LED control which is inherited from Vega 10 took out so much of the PP code
Interestingly
I found this line in vega12_processpptables.c
#define VEGA12_ENGINECLOCK_HARDMAX 198000
Engine Clock hard Limit is 198000/100 Mhz = 1.98 GHz
This value is used in the overdrive engineClock limit calculation. It is read via SMC for Vega 10 and others, probably it is temporary.
From my experience with the code on the RR and Vega 10 last year on how it eventually matches the HW, I would say it is most likely indicative of their target.
It must have escaped Alex Deucher or someone because this is completely a new file and they probably didn't bother to check line by line. Usually on announcement the definitive set of patches are pushed.
Vega 12 with the new Aquabolt and higher clocks are perfect recipes to kick another round of Vega dust