The incomparable Luther Vandross gets his just due in “Luther: Never Too Much,” an overdue but deeply rewarding documentary that looks at the life and career of the late RB singer, who died in 2005 at the age of 54.

The documentary is now in theaters, after premiering at last year’s Sundance Film Festival and airing on CNN in January.

Writer and director Dawn Porter paints this loving portrait of Vandross, tracing his career from his early work on “Sesame Street” and with David Bowie to his own solo output. It looks at his struggles with his weight, the secrets of his sexuality and the power of his artistry, and the mark he left on the music industry and beyond.

Vandross, in archival interviews, speaks of the importance of seeing the Supremes on “Ed Sullivan” when he was a child. It wasn’t just their vocals or their stage presence with which he was fixated, but their costumes, and those fashions left a lasting impression on Vandross that he carried through to his own stage presentation.

When he finally got the chance to be the center of attention, that is. Vandross spent years working his way up the music industry ladder, singing commercial jingles and doing background vocals before striking out on his own. It was Roberta Flack who urged Vandross to give his own solo career a go, and once he released “Never Too Much” in 1981, there was no looking back.

Porter (“John Lewis: Good Trouble”) roots “Never Too Much” in celebration, though Vandross’ up-and-down weight fluctuations are a necessary part of her storytelling. As are the rumors that dogged Vandross about his sexuality, though Porter doesn’t dwell on the issue; she touches it and then moves on, checking the box but not digging into tabloid territory.

What rises to the top are Vandross’ velvety vocals and his jubilant presence, and his ability to make listeners swoon or crumble into tears with the power of his voice. (“Dance With My Father” remains a tearjerker to this day.) “Never Too Much” isn’t enough; by the end, it still feels like it’s too early to say goodbye to Luther.