S.S. Rajamouli has worked with some of Indian cinema’s biggest stars, but Mahesh Babu managed to surprise him in unexpected ways. “As an actor, not much surprised me, because I was watching his films from a very long time. I know what he is capable of,” the “RRR” director says of working with Babu for the first time on “ Varanasi .” “What came as a surprise is his work ethic.” Chief among those surprises: Babu’s strict discipline around mobile phones. “He comes into the office without his phone.