Smith just posted a tribute to his co-star on Facebook ... writing, "Some of my greatest lessons in Acting, Living and being a respectable human being came through James Avery."
He added, "Every young man needs an Uncle Phil. Rest in Peace."
Smith also included a photo with Avery and other "Prince" cast members taken the last time they all got together.
We broke the story ... Avery died on Jan. 1 after experiencing complications from open heart surgery. He was 68.
