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Mac OS Monterey running on Mac Pro 5,1 patched with Open Core Legacy Patcher

I have observe the following odd behaviour.

  • Attach a microsoft mouse to one of the back USB ports. Works.
  • Detach and plug in on front port. Mouse LED flashes once, and mouse does not connect.
  • Detach and plug in on back port again. LED flashes. No connect.
  • Reboot mac, with mouse attached with either port. Works.
  • Attach a hub to the mac, using one of the ports that the mouse doesn't work on. Attach mouse to hup. Works.

I have seen this behaviour with USB keyboards too.

I have another mac running Big Sur. Unplugging and repluging in USB devices works as expected there.

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    I read this somewhere recently, but I can't remember where :\ It's an issue specific to OCLP Mac Pros; something in the USB hardware/firmware is causing this. There are two types of negotiated connection [again can't remember the names] Replugging calls the wrong type, connecting a hub makes the hub call the correct type which then reconnects other peripherals just fine. You might have to look at OCLP's site to figure out what the fault is & whether they think they may be able to correct it.
    – Tetsujin
    Commented Mar 22 at 10:22
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    …or someone might be able to figure out from my vague waffling what exactly I mean, & know where to get the correct full info ;)
    – Tetsujin
    Commented Mar 22 at 10:25
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    @Tetsujin Your comment should be on the half-assed answer I posted below. (rueful grin)
    – Sherwood Botsford
    Commented Mar 23 at 14:13

1 Answer 1

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Partial answer here: Legacy UHCI/OHCI support in Ventura #1021

Nutshell: Mac Pro implements USB 1.1 and 2.0 on separate controllers, with the controller chosen when a device is added. Connecting an older low power older device such as a mouse or keyboard forces that controller to switch to the 1.1 controller.

Added: I think that the hardware defaults to 2.0 but that if present on power up, it will attach to a 1.1 device. This explains the ability to deal with a 1.1 mouse on power up. In addition, when the device is disconnected, the port goes back to 2.0. In OCLP versions of pushing a later OS on earlier hardware, the machine doesn't know how to switch back from 2.0 to 1.1.

By attaching a USB 2.0 hub the controller remains in 2.0 mode, and the older device can still be used.

This explanation contains errors, and is incomplete. I invite corrections.

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