DP_USB4_DRIVER_ID
dpcd_dp_tun_data[DP_USB4_DRIVER_ID - DP_TUNNELING_CAPABILITIES_SUPPORT] & 0x0F;
DPTUN_REG(DP_USB4_DRIVER_ID) | \
u8 drv_id = tunnel_reg(regs, DP_USB4_DRIVER_ID) & DP_USB4_DRIVER_ID_MASK;