What is "form rendering"?
Sorry I meant "form of rendering"
Which Sea Islands do you have?
Radeon R5 M430. I checked it again and it seems to be Southern Islands.
I am not sure.
Which Debian are you using?
Debian Testing
Which DDX driver are you using?
I am not sure what is DDX driver. I installed firmware-amd-graphics in
past and it worked automatically. However, a recent update broke it.
Do you have in your grub stanzas radeon.cik_support=0 amdgpu.cik_support=1 ???
I tried both `radeon.cik_support=0 amdgpu.cik_support=0` and
`radeon.si_support=0 amdgpu.si_support=1`. It seems that the latter
works from the looks of `lspci -k`.