I use U-Boot with the CM4 and had to apply a minor patch to get USB working. I also have a patch which copies some of the firmware modified device-tree into a U-Boot loaded device tree you may find helpful:

https://github.com/cdsteinkuehler/br2rauc/tree/master/patches/uboot

I also got a list of all the things the closed-source firmware is doing behind the scenes before loading the "kernel" (whether that's Linux or U-Boot) which might be of interest:

https://forums.raspberrypi.com/viewtopic.php?p=1974233#p1974233

On 3/14/2023 9:17 AM, Mario Lombardo wrote:

Dear u-boot list members,

I just experience issues with the RPi CM4 Module and U-Boot.

I try to migrate a linux (Raspi Bullseye) from direct loading to use U-Boot as loader. When I load the CM4 direct using the PI-loader (config.txt), everything works. But when I change the kernel to “u-boot.bin” in the config.txt, no USB is working at all (neither within U-Boot nor within Linux).

U-Boot> version U-Boot 2022.10 (Mar 14 2023 - 14:47:34 +0100)

arm-linux-gnueabihf-gcc (Debian 10.2.1-6) 10.2.1 20210110 GNU ld (GNU Binutils for Debian) 2.35.2 U-Boot> usb start starting USB… No working controllers found U-Boot>

The U-Boot is compiled as rpi_4_32b_defconfig with DWC2 enabled: […] CONFIG_USB_DWC2=y CONFIG_USB_DWC2_BUFFER_SIZE=64 […]

Now when I start Linux as follows:

fdt addr ${fdt_addr} fdt get value bootargs /chosen bootargs setexpr bootargs sub "console=ttyAMA0" "console=ttyS0" “$bootargs” fatload mmc 0:1 ${kernel_addr_r} “kernel7l.img” bootz ${kernel_addr_r} - ${fdt_addr}

I´m able to login using the serial console. But I can not any USB Device:

pi:~# lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The Device Tree seems to be identical to the version without U-Boot:

pi:~# dtc -I fs -O dts /sys/firmware/devicetree/base/soc/usb@7e980000/ -f /dts-v1/;

/ {         power-domains = <0x13 0x06>;         compatible = "brcm,bcm2835-usb”;         clocks = <0x19>;         clock-names = “otg”;         phy-names = "usb2-phy”;         g-rx-fifo-size = <0x22e>;         status = “okay”;         #address-cells = <0x01>;         interrupts = <0x00 0x49 0x04 0x00 0x28 0x04>;         #size-cells = <0x00>;         phandle = <0xb7>;         phys = <0x1a>;         reg = <0x7e980000 0x10000 0x7e00b200 0x200>;         dr_mode = “host”;         g-tx-fifo-size = <0x200 0x200 0x200 0x200 0x200 0x100 0x100>;         interrupt-names = "usb\0soft”;         g-np-tx-fifo-size = <0x20>;         name = “usb”; };

However I cannot see any USB Devices using U-Boot.

Any ideas? What is U-Boot doing different during boot compared to the default boot process?

Thank you very much.

Mario