XHCI driver on Pi4

At present the XHCI driver on the Pi 4 (13-Sep-2020 daily build) does not support a USB hub plugged in to one of the four sockets.

The symptoms are that with a hub plugged in, to which is attached a SATA drive, then:
(1) Director hangs, stiffing the machine – remove either Director or the hub and all is fine.
(2) if the hub is unplugged and plugged in to a different USB socket there is an AODT at offset +416C in the XHCI module and the machine is stiffed.

Also some brands of USB pen drive are marginal with XHCI (on Pi4 and Titanium) but that is a separate thing that is not worth pursuing.

Hi Chris,

I have a Aukru USB 3.0 hub plugged to to my Pi4 running the latest RC16 and Beta Rom and don’t see any issues when plugging/unplugging the Hub in to different sockets.

I have the Hub powered and have also tried usb sticks in it and they work with no issues when plugging/unplugging as well.

I however do not use Director.

Hub details:
New USB Device found:

Hope this helps.

I am not so concerned over whether a particular hub works or not. However it should not stiff the machine. Errors should be handled correctly.

I am not so concerned over whether a particular hub works or not. However it should not stiff the machine. Errors should be handled correctly

Agreed but you also need to look at the whole picture hence why I gave my hub details including the class etc as that gives granularity of information that may be useful.

Is your hub powered or non powered.
If as you say you take Director out of the equation it works fine then is it an interaction with that application and what is it configuration and what does it look at.

All this will give greater information to help diagnose any issue in the OS elements.

However it should not stiff the machine.

There’s what should and there’s what does and sometimes they ain’t at all similar.

Errors should be handled correctly.

In my (limited) experience with keyboards (they can stiff the machine too), there’s a bunch of protocols that these things are supposed to support, and then you get the outliers that want to handle fifty key rollover and gestures and stuff, and so they splat out a much larger wodge of data than is expected and it all goes wrong.
Linux doesn’t handle these sorts of things terribly well either, the driver usually crashing.
Which is more or less what RISC OS does, but when your code, buffers, and stack are the same ones (and same privilege) as the kernel, screwing up the stack doesn’t mean the process gets terminated, it means the entire OS poops itself.

As to Director showing up an issue with a hub… That’s a bit weird. I wonder if Director is doing something that is the real issue, and when Director isn’t being used the problem hasn’t gone away, there’s just nothing performing the steps that trigger it.
I say this because hubs are supposed to be largely invisible to anything other than the USB subsystem…

In the interests of pursuing this further I picked up the nearest memory stick to hand, a USB3 SanDisk Ultra 128GB, plugged it directly into a USB2 port on the RPi4. It connected without issue revealing itself to be Fat32 but it readily stiffed the RPi4 on read operations. It did the same to the Titanium. Using Raspberry Pi OS to see what the pen had previously been used for showed it to be an Ubuntu 19.10 installer. The stick had previously used with the Pi for performance tests but with the OTG port, it had RISC OS speed tests on it.

Reformatting it on the Pi to be either SCSI or Fat32 and there were no further issues.

Not that this is very helpful but it does illustrate a pen stiffing RISC OS in use as opposed to stiffing it on plug in.

No external hubs involved in this case.

when Director isn’t being used the problem hasn’t gone away, there’s just nothing performing the steps that trigger it.

When the (presumably same) problem occurs without Director running it is an AODT at +416C in module XHCI.