parlio_rx_unit_config_t::::free_clk field

Whether the input external clock is a free-running clock. A free-running clock will always keep running (e.g. I2S bclk), a non-free-running clock will start when there are data transporting and stop when the bus idle (e.g. SPI). This flag only takes effect when select PARLIO_CLK_SRC_EXTERNAL as clock source