I'm having some weird issues. I have a midi keyboard and a audio interface, both attached by USB to my mac pro.
The mac has the built in 3 ports on the back, 2 ports on the front.
At present it will go along find, but occasionally the sound stutters. I get a 1/2 to 1/2 second block of the sound repeating 2-3 times. This always throws me when I'm playing.
This can happen, but less often, with youtube videos played through the audio interface, and even less often with sound played through the internal speakers.
I have also had the following happen:
I have a mouse plugged into one of the back ports. If I unplug it, and plug it in on another port, the LED flashes once, and the mouse is not recognized. If I leave it plugged in, and reboot the machine, it is recognized.
This also happens with keyboards.
On the OCLP web site, I found this:
Intermediate issues with USB 1.1 and Bluetooth on MacPro3,1 - MacPro5,1
For those experiencing issues with USB 1.1 devices (such as mice, keyboards and bluetooth chipsets), macOS Big Sur and newer have weakened OS-side reliability for the UHCI controller in older Mac Pros.
UHCI is a USB 1.1 controller that is hooked together with the USB 2.0 ports in your system. Whenever a USB 1.1 device is detected, the UHCI controller is given ownership of the device at a hardware/firmware level.
EHCI is the USB 2.0 controller in older Mac Pros
Because of this, we recommend placing a USB 2.0/3.0 hub between your devices and the port on the Mac Pro. UHCI and EHCI cannot both be used at once, so using a USB hub will always force the EHCI controller on.
- Alternatively, you can try cold-starting the hardware and see if macOS recognizes the UHCI controller properly.
Does the above explain the behaviour of the unrecognized device after moving it?
Does it explain the audio behaviour?
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