I'm a little late with this news about La La Land.
This morning I was on twitter (it happens rarely) and the dear girls at Gosloving did re-tweet this video few days ago.
It's a brief interview taken by ET Canada with JK Simmons at TIFF on Sept. 15. In this clip he talks also a little about his role in the movie.
He admits he has just a cameo in the movie (he plays the Boss...) and Ryan and Emma are doing all the singing and dancing parts.
The shooting is still on GosAdd, so stay tuned..... and Gos.