Jamieson, Fausset and Brown on Philippians 2:11

11. every tongue--Compare "every knee" (Php 2:10). In every way He shall be acknowledged as Lord (no longer as "servant," Php 2:7). As none can fully do so "but by the Holy Ghost" (1Co 12:3), the spirits of good men who are dead, must be the class directly meant, Php 2:10, "under the earth."

to the glory of God the Father--the grand end of Christ's mediatorial office and kingdom, which shall cease when this end shall have been fully realized (Joh 5:19-23, 30; 17:1, 4-7; 1Co 15:24-28).