SS Rajamouli, in a recent interview has spoke about collaborating with Pawan Kalyan. The director has clarified explicitly on why he hasn't had the chance to work with the star yet.
The Bahubali series director mentions that the reason for this is due to the fact that Pawan Kalyan is not just an actor, but also a person whose public life is of as much importance as his career. In fact, since the actor spends more time for public service, it is more difficult to obtain too much exclusive time from Pawan specially for shoot.
When asked about the similarity of generosity between the two of them, Rajamouli mentioned that when compared to Pawan Kalyan, what the director does does not amount to even 0.5% of Pawan's contribution towards the society.