Jimmy Garoppolo has nothing to fear about losing endorsements or pissing off his bosses just because he's dating a porn star ... so says none other than NBA team owner and "Shark Tank" star Mark Cuban.
Mark says he's had players on the Dallas Mavericks who have dated porn stars in the past, and it's never been an issue -- with one caveat. If they try to hide it, they're screwed.
Cuban thinks Jimmy actually did himself a big favor because he's coming off as authentic ... and, in the world of advertising, there's nothing more important than being real.
TMZ broke the story .. the 49ers QB took porn legend Kiara Mia out to dinner in Bev Hills Wednesday night.