USB issues on Odroid-C1

Martin Blumenstingl martin.blumenstingl at googlemail.com
Sun Dec 9 12:12:49 PST 2018


Hello Brian, Hello Mauro,

I debugged USB issues on my Odroid-C1 today which doesn't detect USB
devices connected to any of the four USB ports.
This issue only exists on the mainline Linux kernel - USB works fine
with an older Armbian image on the same board (this is why I assume
that the hardware itself is fine and I'm chasing a software issue).

version code on my PCB:
ODROID-C1+ REV 0.4 20150615

The USB hub is detected fine since the mainline kernel is pulling
GPIOAO_4 (GPIOAO.BIT4) HIGH.
I have also seen that there's a PWREN signal (GPIOAO.BIT5) in the
schematics. I verified that this goes to the EN pin of the Richtek
RT9715EGB next to the micro-USB connector.
I'm not sure if the same signal has any impact on the USB-A ports.

I started to look for any clues in the schematics so I started
measuring the voltages at MOSFET "Q5".
Here are my results:
armbian:
- 1: 3.3V
- 2: 0V
- 3: 0V

mainline:
- 1: 0V (during boot it goes to 3.3V for 1 second or two, but then
goes back to 0V)
- 2: 0V
- 3: 3.3V
(I did two measurements: with GPIOAO_5 LOW and GPIOAO_5 HIGH - I get
the same result in both tests)

the pin names for the numbering in the schematics:
- 1 = Drain
- 2 = Source
- 3 = Gate

Can you please look into my test results and let me know if you have
any idea what we may be doing wrong in the mainline kernel? I can also
do more measurements, please let me know what to measure exactly.


Thank you!
Regards
Martin



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