Reboot after usb start in U-Boot


I wanted to reinstall the Toradex Easy Installer with a USB drive, but the Viola board with iMX7 Dual seems to have a problem with USB itself. It automatically reboots without error when using USB. After running usb start I get the following via serial output:

Colibri iMX7 # usb start
starting USB...
USB0:   USB EHCI 1.00
scanning bus 0 for devices... 1 USB Device(s) found
USB1:   USB EHCI 1.00
scanning bus 1 for devices... 

U-Boot 2016.11-2.8.7+g5c2d46b325 (Jun 10 2020 - 17:13:37 +0000)

CPU:   Freescale i.MX7D rev1.3 996 MHz (running at 792 MHz)
CPU:   Extended Commercial temperature grade (-20C to 105C) at 42C
Reset cause: POR
DRAM:  512 MiB
PMIC:  RN5T567 LSIVER=0x01 OTPVER=0x0d
NAND:  512 MiB
Video: 640x480x18
In:    serial
Out:   serial
Err:   serial
Model: Toradex Colibri iMX7 Dual 512MB V1.1D, Serial# 06437741
Net:   FEC0
Hit any key to stop autoboot:  0 
Colibri iMX7 # 

It happens every time when a USB device is attached (drive, keyboard,…) and even sometimes when nothing is attached and I run “usb start”. Any idea why this can happen or how I can get additional error messages? Can this be a power problem? (I use 5V, 3A power adapter, idle measuring 5.13V)

Additional info: The same happens if I boot linux and a usb-device is attached:

[    1.367896] ci_hdrc ci_hdrc.0: EHCI Host Controller                          
[    1.374812] ci_hdrc ci_hdrc.0: new USB bus registered, assigned bus number 1 
[    1.414134] ci_hdrc ci_hdrc.0: USB 2.0 started, EHCI 1.00                    
[    1.422510] hub 1-0:1.0: USB hub found                                       
[    1.428315] hub 1-0:1.0: 1 port detected                                     
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U-Boot 2016.11-2.8.7+g5c2d46b325 (Jun 10 2020 - 17:13:37 +0000)                 
CPU:   Freescale i.MX7D rev1.3 996 MHz (running at 792 MHz)

Hi @msx23

I could not reproduce the error.
What other peripherals did you connect to the viola carrier board?
Did you measure the 5V voltage on Carrier Board during USB Start command?

Thanks and best regards,

Only power, serial and usb attached, nothing else. I didn´t measure during usb start yet. I will do that if I have the same problem in the future. But for now, I was able to start the Easy Installer with an SD Card. I was just curious what the problem could be…

Thanks for your Input.
Let us know if the issue occurs again.

Best regards,