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I am seeing the following message in the Linux kernel log:

usb usb1-port5: disabled by hub (EMI?), re-enabling...

After that USB devices are disconnected. In some cases they reconnect immediately, in other cases they don't. In the latter cases, I also see:

usb usb1-port5: Cannot enable. Maybe the USB cable is bad?

What causes these issues and how to avoid the bad effects?

In this particular case, a wireless USB stick is connected directly to a USB port. The issue does not correlate to a particular time of day. Using a different USB port makes no difference. Using a different wireless USB stick makes no difference. Using a different mainboard makes a difference. Disconnecting other USB devices makes no difference.

Even though presenting details here, answer can and should try to cover more settings to be useful to others.

Ola Ström
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Helmut Grohne
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2 Answers2

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I don't understand why. Physically moving the wireless USB stick from the mainboard by connecting it to an external USB hub connected with a 2 meter cable made the disconnect problems go away.

Helmut Grohne
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Have been experiencing this with stations at a high EMI location. It is very bad. I worry about frying the device, but more so feel the pain of major hesitation when the original poster's error message comes up. The machine becomes partially unresponsive. Maddening motivator to fix it.

I have intermediary hubs. I have grounding as best I can. But there are still issues.

Turns out that a "ferrite core" is designed to help mitigate these issues: https://en.wikipedia.org/wiki/Ferrite_core

Solution mentioned here and about to try adding ferrite cores:

https://electronics.stackexchange.com/a/33965/162810

music2myear
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digitalextremist
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