Android CPU stall on connecting USB for adb

[Zaxter]

I'm using A20_android_422_TS_USB_UART_I2C_WIFI_LAN_HDMI_LCD_800x480_release_3.img from the wiki, running on a Olinuxino Micro 4GB. I am able to boot normally.

However, I don't see the shell on debug UART. But that maybe disabled (?).

Also, I'm not able to access the adb shell. As soon as I plug in the micro USB, I get CPU stall messages on the UART and the system hangs.
The moment I plug in the micro USB, I see the 'USB debugging connected' toast on my HDMI connected LCD, and the system hangs.

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INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1, t=24007 jiffies)
INFO: Stall ended before state dump start


At times I also get these messages:

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axp_mfd 0-0034: failed reading at 0x27


adb doesn't find the board.

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$ ./adb shell
error: no devices/emulators found



FWIW, I'm using a 12V power adapter to power the board.
How can I get adb shell to work?

[Zaxter]

This is strange. I couldn't find any other post with same problem on the forum.

I'm starting to think if there's something wrong with my setup (power cable, usb cable, etc.), or maybe this is some hardware issue.
Sadly I don't have another board I can test with.

[lalito]

Hello I had a similar problem and disconnect the earth monitor, and there the adb link is fixed. A potential differential appears through the grounding of the hdmi connector cap of the A20 board

[Zaxter]

Thanks @lalito... This (partly) solves my problem.

I don't have the stalls now, but I still can't get adb to work...

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$ ./adb shell
error: no devices/emulators found