tunnel_reg_ptr
if (drm_dp_dpcd_read_data(aux, address, tunnel_reg_ptr(regs, address), len) < 0)
return *tunnel_reg_ptr(regs, address);
tunnel_reg_ptr(®s, DP_TUNNELING_OUI),
dev_id_len(tunnel_reg_ptr(®s, DP_TUNNELING_DEV_ID), DP_TUNNELING_DEV_ID_BYTES),
tunnel_reg_ptr(®s, DP_TUNNELING_DEV_ID),