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usb over-current condition on ls1021a board

Question asked by Matthias Fuchs on Feb 29, 2016
Latest reply on May 20, 2016 by ufedor

Hi,

 

we ran into this issue on a ls1021a based custom board. Design is very similar to the

TWR board. But without the USB 3.0 hub.

 

During boot the linux kernel reports an over-current condition and port power is then disabled. So no USB devices are detected:

 

[ 3028.127516] hub 1-0:1.0: USB hub found

[ 3028.129991] hub 1-0:1.0: 1 port detected

[ 3028.143710] hub 2-0:1.0: USB hub found

[ 3028.146156] hub 2-0:1.0: 1 port detected

[ 3028.449817] hub 1-0:1.0: over-current condition on port 1

[ 3028.669099] hub 2-0:1.0: over-current condition on port 1

 

The kernel comes from the SDK 1.9 with only minor changes in its configuration.

The SDHC field in the RCW is set to 3 (for DRVVBUS/PWRFAULT). Our USB power switch is connected to these pins. DRVVBUS is low and PWRFAULT is high. That's the problem.

We changed the RCW[SHDC] to 1 so that the DRVVBUS can be controlled as GPIO. As GPIO we could enable DRVVBUS, the 5V were switched on and finally USB devices were detected.

 

So where does this over-current condition comes from? What might cause this strange problem?

 

USB does also not work in u-boot. But it does on the TWR board.

 

Matthias

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