A20-OLinuXino-MICRO disabled power in USB, modules autoload


I have created a bootable SD card with excellent instruction from
(debian-9.3-minimal-armhf-2017-12-09 image with 4.14.15-armv7-lpae-x3 kernel).
It has booted on my A20-OLinuXino-MICRO with no problem.
I have found a couple of issues, however. These issues do not appear with original Olimex image (that has some other issues, however)…

  1. There no power in USB connector. The devices plugged into externally-powered USB hub, connected to the board are perfectly visible. Is there any way to enable the USB power on boot?

  2. No kernel modules load by default. No sound, no power controller… Is it a bug or a feature?

Thank you!

Hi Rostislav,

Which USB Connector? The Dual USB ports next to the Ethernet connector or the OTG?

The Dual ports are working for me, while the OTG port is showing up:

debian@arm:~$ dmesg | grep musb
[    1.823960] musb-hdrc musb-hdrc.1.auto: MUSB HDRC host driver
[    1.823979] musb-hdrc musb-hdrc.1.auto: new USB bus registered, assigned bus number 3
[    1.824479] usb usb3: Manufacturer: Linux 4.14.16-armv7-x4 musb-hcd
[    1.824485] usb usb3: SerialNumber: musb-hdrc.1.auto

But I see an extra:

[    1.834338] usb0-vbus: disabling

So looks like the vbus regulator is going down…

Starting with v4.14.x we are compressing the modules by default:


This saves some space:

debian@arm:~$ du -sh /lib/modules/*
28M	/lib/modules/4.14.16-armv7-x4
77M	/lib/modules/4.9.78-armv7-x6

However, if your build platform doesn’t have the “kmod” package built with the compression option (now finally enabled by default in Debian Sid/Buster), you’ll need to run this command on your end device:

sudo depmod -a

Which modules are we missing for sound/power?


Hi Robert,


Modules are perfectly loadable.
The build platform is Ubuntu 16.04 LTS. kmod is version 22, build with "-XZ -ZLIB -EXPERIMENTAL"
sudo depmod -a
was the missing part. Probably, worth adding to the instruction.

With USB, I was, probably not clear… Sorry. The Dual USB ports are in question. (I have not checked OTG.)
The ports are perfectly visible from the system. Anything, plugged to an externally-powered USB hub works fine. USB-powered devices, plugged to ether of the ports are not visible (according to lsusb)… Could the reason be that i use Revision F of the board, manufactured back in 2014?


Hi Rostislav,

Looking at Olimex’s schematic’s that revision should be fine. The 5volt rail powers the usb port’s, which does lead to the question, how are you powering your Micro board? DC jack, battery, or usb?