AMDGPU_DOORBELL64_sDMA_ENGINE0
AMDGPU_DOORBELL64_sDMA_ENGINE0 + (i >> 1);
AMDGPU_DOORBELL64_sDMA_ENGINE0 + 0x200 + (i >> 1);
(AMDGPU_DOORBELL64_sDMA_ENGINE0 << 1) //get DWORD offset