Hi,
Currently in RMII mode we are using 25 Mhz crystal mode
The KSZ8041RNL generates the 50MHz RMII REF_CLK and outputs it to the MAC
attached is the block diagram for your reference.
In pin configuration RGMII_TXC should be configured as ENET0_RCLK50M_IN input right?
IMX8QXP_ENET0_RGMII_TXC_CONN_ENET0_RCLK50M_IN 0x06000061
Also let us know the pad settings 0x06000061 is correct