It is recommended to use I2S as a slave to an external master that drives the bit clock and frame sync. The frame sync timings are marginal when I2S generates the BCLK and FS signals
When I2S is configured as a slave, frame synch needs to be delayed to meet data sheet timing requirements. Implement an RC delay on the I2S_FS trace and size R and C to satisfy the timing requirements. For more information, see the device-specific data sheet.
To ensure synchronization among multiple I2S busses, it is recommended to use one external master to drive clocks to multiple slaves (including the C55xx).