The code blindly assumes a TIS interface is present in case both CRB and FIFO checks fail. Check the InterfaceType for TIS instead and only return Tpm2PtpInterfaceTis in case it matches, Tpm2PtpInterfaceMax otherwise. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>