SGTL5000 codec - No PCM or I2S Tx output from WP8548



I am currently working on an extension board providing an external audio codec (using the PCM output available on the IoT connector).
For now, I am focused on the Linux kernel modification in order to detect and initialize the codec but this is not a 2 days work.
For now I managed to initialize the codec through I2C and get a PCM clock on the IOT pin but I do not see any PCM data going to the codec.

I am not sure if I am on the right way to achieve my goal.

Is there some tips/good practices to do that ?

Best Regards