I can't really parse what you're talking about here (perhaps some of that context would have helped...) but it doesn't seem to be the clocking of the I2S bus which would normally be what master and slave would be talking about. It is the clock setting of I2S bus master or slave. If I am playing music only, I set TX as master. All others are slave. If I am recording only. I set RX as master. All others are slave. If I am playing and recording at same time, I set first coming stream as master second coming stream as slave. If I shut down first stream before second stream, then I will set the second stream as master, otherwise there will be no clock/FS signal on the I2S bus to maintain the second stream to its end. Hope it is clearer.
