AMDGPU_DOORBELL64_sDMA_ENGINE1
AMDGPU_DOORBELL64_sDMA_ENGINE1 + (i >> 1);
AMDGPU_DOORBELL64_sDMA_ENGINE1 + 0x200 + (i >> 1);
: (AMDGPU_DOORBELL64_sDMA_ENGINE1 << 1); // get DWORD offset