USB to Serial EMI Error Recovery

[ken 0]

PL2303 Usb To Serial Use TinkerBoard2

USB port nn disabled by hub (EMI?), re-enabling

It is not recognized automatically after an error occurs.

dmesg Message

[   10.052654] usb 5-1.1: Device not responding to setup address.
[   10.263675] usb 5-1.1: device not accepting address 6, error -71
[   10.300419] usb 5-1-port1: unable to enumerate USB device

But Power OFF -> ON  It is recognized normally.

FTDI Usb To Serial Use TinkerBoard2  - It is automatically recognized again after EMI Error occurs.

PL2303 Driver Kernel Bug?

 

[tooz 53]

hello @ken, 

If the OS image you're using is with kernel v.4.4, then there is no difference between Tinker Board & Tinker Board 2S'  PL2303  driver. 

Tinker Board's USB controller is dwc2 and Tinker Board 2S' USB controller is xhci, the recovery mechanism are different.

[tooz 53]

hello @ken, 

Error -71 is a protocol error. When it occurs, it's likely that the peripheral device could get stuck in any state. Some peripheral devices have the ability to recover from this kind of state by host control, but some don’t.

Looks like your PL2303 device did not respond to any request from host. So it probably can only be recovered by power resetting the PL2303 device. Could you try to unplug and replug the PL2303 device and see what happens?

[ken 0]

Hello @tooz,

It seems that reset is not possible in the error state.

If you unplug the PL2303 plug and reinstall it, it will be recognized normally.

Thank You.