Whereas Hversu and Ynglinga saga don't inform about Halfdan's mother, Hervarar saga provides the information that she was Hild, the daughter of the Gothic king Heiðrekr Ulfhamr, the son of Angantyr who defeated the Huns.
It then tells that Halfdan had the son Ivar Vidfamne, who attacked Ingjald Ill-ruler, which led to Ingjald's suicide by burning down his own hall at Ræning together with all his retinue. After this, Ivar Vidfamne conquered Sweden.
Read more about this topic: Halfdan The Valiant