The Radxa ROCK 5B board has no support for USB 2.0 Host in the U-boot bootloader.

There are two USB 2.0 ports (number 7 in the photo) and two USB 3.0 ports (number 8 in the photo). However, the top USB 3.0 port can also work in 2.0 mode.

Hardware description of the Radxa Rock-5B board. Source: https://wiki.radxa.com/Rock5/hardware/5b

The Inno2 USB PHY driver in U-boot requires changes to be able to correctly start the PHY variant that is present in the RK3588 SoC. The regulator subsystem in U-boot needs to be able to count how many PHYs have requested the power regulator, such that disabling one PHY does not involuntarily cut off the power for the other PHY.

The device tree of the board needs to correctly describe the power sequence, the USB host controller, the PHYs, and all the connections between them. And lastly, the generic OHCI and EHCI drivers can work directly with the USB controller in RK3588.

After implementing all the required changes, the USB Host works, and we can connect the USB mass storage device and Ethernet dongle.

If you are interested, we have a dedicated tree at Collabora that includes the mentioned support: https://gitlab.collabora.com/hardware-enablement/rockchip-3588

The beauty of Open Source is that we can reuse code written by many other people, keep their authorship, and credit them for their work, without needing to reinvent anything.

Hence, my work as the last step into getting this into mainline U-boot is nearly finished. The patches along with all my required changes are already public:

https://marc.info/?l=u-boot&m=168191161609668&w=2

and

https://marc.info/?l=u-boot&m=168191189309879&w=2

And yet another beautiful part of Open Source is that anyone can comment, review, and test these changes before they are integrated into mainline U-boot!