[OpenCL] Pairing up RDNA1 gpus with RDNA2 on mobo without Pci Atomics

[Kayote]

hey guys... maybe this is a tough question. I know that with motherboards older than AMD B5XX you cannot use two or more GPUs simultaneously with OpenCL. Afaik this happens with RDNA cards that don't support OpenCL "legacy mode".
For example if you have two 5700XT since those cards support legacy OpenCL mode it will work on a b450 for example. But two 6800XT won't work on a b450, because those mobos lack Pcie Atomics.
but here is my question what about mixing up 1 RDNA1 card with a RDNA2 gpu? 1 card will work in OpenCL legacy mode and the other one in RocM mode ? will that work?

[agd5f]

Vega and newer GPUs no longer require PCI atomics.

[Kayote]

Rocm documentation is not very clear I get this

sudo lspci -vvv -s 01:00.0|grep Atomic && sudo lspci -vvv -s 0b:00.0|grep Atomic  
                        AtomicOpsCap: 32bit- 64bit- 128bitCAS-
                        AtomicOpsCtl: ReqEn-
                        AtomicOpsCap: 32bit+ 64bit+ 128bitCAS-
                        AtomicOpsCtl: ReqEn+

and only 1 card works in RoCM mode . I have a B450 Aorus Pro Wifi .
Don't know what the plus and minus signs actually refer to.
Anyway was able to get both cards working in legacy mode with latest amdgpu drivers, using this reddit guide (just in case by chance someone else is having a similar issue)

https://www.reddit.com/r/gpumining/comments/ptmyjd/ubuntu_20043_amdgpu_2130_opencl_rocr_rocm/

[agd5f]

Make sure you have new enough firmware.