(In reply to mikhail.v.gavrilov from comment #30)
> Created attachment 143908 [details]
> dmesg without patches
> 
> Without patches backtrace are looks like initial deadlock backtrace.

Can you please apply back the first 2 patches and then add the following - 

Install trace-cmd utility
Type sudo trace-cmd start -e dma_fence -e gpu_scheduler -e amdgpu -v -e
"amdgpu:amdgpu_mm_rreg" -e "amdgpu:amdgpu_mm_wreg" -e "amdgpu:amdgpu_iv"
to enable kernel event tracing log

After hang happens 

cd /sys/kernel/debug/tracing && cat trace > event_dump, upload this dump here.