tdsaExpander_s
struct tdsaExpander_s;
struct tdsaExpander_s *RootExp; /* Root expander of discovery */
struct tdsaExpander_s *tdExpander;
struct tdsaExpander_s *tdUpStreamExpander; /**< the pointer to the upstream expander device */
struct tdsaExpander_s *tdCurrentDownStreamExpander;
struct tdsaExpander_s *tdReturnginExpander;