iW-RainboW-G36M SOM, USB3320 USB PHY is used with a reference clock frequency of 24MHz. The USB3320 PHY also supports a 38.4 MHz reference clock.
If planning to change the clock frequency for the USB1 controller, please note that the reference clock can be configured through REFSEL pins strapping of the USB3320.
On G36M SOM, MIO pins are assigned to the GEM3 interface. Since the GEM3 RGMII and USB1 ULPI signals are multiplexed on the same pins, only one interface can be used at a time. Therefore, please make sure that GEM3 is disabled in the Zynq UltraScale+ MPSoC IP configuration in the Vivado design when using USB1.
Also, modifying the USB PHY reference clock will not impact the Linux Device Tree or driver.
For further inquiries, please get in touch with mktg@iwave-global.com
Please find the detailed G36M product information in the below link,