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Linksys USB2HUB4 #331

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ChaoticEnigma opened this issue Apr 2, 2021 · 3 comments
Closed

Linksys USB2HUB4 #331

ChaoticEnigma opened this issue Apr 2, 2021 · 3 comments

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@ChaoticEnigma
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I know it's already listed, but I wanted to add some details I might have about the Linksys USB2HUB4.

Current status for hub 3-2.1 [0409:0058 NEC Corporation USB2.0 Hub Controller, USB 2.00, 4 ports, ppps]
  Port 1: 0100 power
  Port 2: 0100 power
  Port 3: 0100 power
  Port 4: 0100 power

I am able to able to disable the VBUS on each port with uhubctl -L 3-2.1 -p 1 -a toggle, tested with a USB voltage/current monitor (not a USB device, only looks at VBUS).

Also interesting, if I overload the VBUS on one of the ports (e.g. with a 1A load), the hub temporarily disables the port without affecting the others, and the port is reported as "off". As below, where port 3 is overloaded:

Current status for hub 3-2.1 [0409:0058 NEC Corporation USB2.0 Hub Controller, USB 2.00, 4 ports, ppps]
  Port 1: 0103 power enable connect [1050:0120 Yubico Security Key by Yubico]
  Port 2: 0100 power
  Port 3: 0000 off
  Port 4: 0100 power

And it seems to return to normal when the overload is removed.
@mvp
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mvp commented Apr 2, 2021

Thanks, this is actually expected behavior for properly implemented USB hub.
Hub should sense OC (overcurrent) condition and disable port for misbehaving device.
Nevertheless, I will add a note in hardware table linking to this - thank you!

@mvp mvp closed this as completed in 7bafc7f Apr 2, 2021
@ChaoticEnigma
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Yes, the overcurrent behavior was expected. But I was a little surprised that the overcurrent disabled state was visible to the host.
You could also add the VID and PID to the hardware table.

@mvp
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mvp commented Apr 2, 2021

Thanks, I will add vid:pid when I need to update table next time.

uhubctl is querying hub directly with USB control messages to get or set power state - thus is why we can see current state properly (provided that USB chip implements it correctly).

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@mvp @ChaoticEnigma