What sad news - a real innovator and a prolific songwriter. Back in my student days in the 90's I went to a club in Minneapolis which he was known to frequent, and he did make a brief appearance. Sad loss
He was incredible, not only in his own interpretation, but also writing songs for others. Vanity6 (Nasty girls), I feel for you (Rufus and Chaka Khan) springs to mind as the biggest hits.....