“That was our very first time ever producing a star,” says Rodgers. “Not only was it a star, it was, like, the star.”

But Rodgers and Edwards helped make that superstar shine brighter than ever: Ross’ classic “Diana” album — released 40 years ago on May 22, 1980 — went on to become the best-selling LP of her career with hits such as “Upside Down” and the gay anthem “I’m Coming Out.” And perhaps more significantly, it set the twirling template for all of the diva dance-pop that would come after that, from Madonna and Janet Jackson to Beyoncé.

It was a tricky, transitional time for Ross at the beginning of the post-disco era. “The disco era ended in the summer of ’79, and she came out the next year,” says Rodgers. “So we had to make a record that wasn’t disco.”

Rodgers and his late partner, Edwards, had proven themselves to be disco dynamos, producing hits such as “Le Freak” and “Good Times” for their own group Chic, as well as Sister Sledge’s smash “We Are Family.” But now they had to show that they were more than just disco, with Ross wanting to court a younger audience. “She didn’t say, ‘Well I’m trying to make an album for the kids,’ ” says Rodgers. “But she knew that’s what we were doing.”

To that end, Rodgers and Edwards “interviewed” Ross before writing a note of music. “For two days she told us her life story, as if we were writing a magazine article,” says Rodgers. “And then we went and we wrote the album. Basically, the reason why it’s just [called] ‘Diana’ is it’s a documentary.”

The first single “Upside Down,” which went No. 1, came directly out of those conversations: “Those were her words actually,” says Rodgers. “She said that she just wanted to turn her whole career upside down, and that was in our notes. But we thought that it would be more powerful in a romantic setting, so we wrote ‘Upside down, boy you turn me.’ And she flipped when she heard it.”

“I’m Coming Out,” the second single, was inspired after Rodgers saw a bunch of “Diana Ross impersonators” in the bathroom at GG’s Barnum Room, a predominantly transgender club in midtown Manhattan. “All of a sudden a lightbulb goes off in my head,” he says. “I had to go outside and call Bernard from a telephone booth. I said, ‘Bernard, please write down the words: ‘I’m coming out.’ And then I explained the situation to him.”

Ross immediately loved the song, connecting with the empowering lyrics: “The time has come for me to break out of this shell/I have to shout that I am coming out.” “But she didn’t understand that that was a gay thing, that that was a person saying, ‘I’m coming out of the closet,’ ” says Rodgers. “She didn’t even get that.”

At least not until Ross played the song for influential WBLS DJ Frankie Crocker. “He thought that that would be Diana saying that she was gay,” says Rodgers.

But Rodgers convinced the singer to stick with the song anyway, selling it as the perfect concert opener to make a regal entrance for the rest of her life. “I said, ‘Diana, this song is gonna be your coming-out song. We think of you as our black queen,’ ” he says. “And I even wrote a [horn] fanfare. I explained to her that it’s just like when the president comes out and they play ‘Hail to the Chief.’ ”