I recently put an Amazon Echo Dot in my home office. It needs USB power; rather than plug in yet-another-power-adapter, I plugged it into a spare port on a USB hub connected to my Mac Mini.
All was well…until I needed to reboot the Mac. Then I noticed two things:
- A normal reboot took a long time to show the login screen (more than a minute, versus the usual 10 seconds)
- Pressing Option during the reboot (to try to reboot from another device) failed – the machine hung, never giving me the screen with devices to try.
I tried resetting NVRAM and the SMC; no dice.
Eventually, I managed to reboot and took a look at the system log; there were many, many error messages like this:
Oct 6 12:52:00 office kernel: 000573.331885 AppleUSB20HubPort@14233000: AppleUSBHostPort::disconnect: persistent enumeration failures
I started disconnecting devices, and when I unplugged the Dot, the messages stopped appearing.
I’m now powering the Dot with its own power supply, plugged into a power strip. It works great, and the Mac Mini is happy, too.