Based on https://forums.raspberrypi.com/viewtopic.php?p=2158890#p2159063 , I would like to ask for exposing information on the GPCLK feature shortly mentioned in the existing RP1 docs draft, and partly introduced in clk_rp1.c, especially the clk <-> GPIO matrix available for general use.

Specifically I am interested in MCLK GPCLK input/output/output tap for I2S which is important for connecting external ADC/DAC chips with MCLK input pin (i.e. all ADC/DAC chips without an internal BCLK -> MCLK PLL).