USB xhci crash under load on 5.14-rc3

this is a reply to a post on linux-usb of Wed, 4 Aug 2021
(https://www.spinics.net/lists/linux-usb/msg215253.html)

In case this problem is still relevant:

I ran into a similar issue with kernel 5.10.0 (Debian Bullseye) and a Fantec external HDD enclosure connected via USB3.1.
I set up a raidz2 with 7 disks, and after a few minutes of heavy use always got:

Feb  6 12:37:29 andromeda kernel: [932663.635942] xhci_hcd 0000:45:00.1: AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x002e address=0xffffffe00000 flags=0x0000]

and all connected devices would go away, leaving zfs rather puzzled.

This link, https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1844858
suggested a conflict with the IOMMU.
The controller is
Advanced Micro Devices, Inc. [AMD] Matisse USB 3.0 Host Controller (prog-if 30 [XHCI]) on an ASRock TRX40 Creator

After disabling the IOMMU in the BIOS, the problem went away so far.

Roman