USB errors lock up Pi 4

[John Klos <john%ziaspace.com@localhost>]

Hi,

I wish I had more hardware with which to test, but I don't, so my data set 
is small.

I have a 4 gig Raspberry Pi 4 with which I've been using an SSD connected 
via USB-3 with UEFI and the kernel loaded from an SD card.

For the last couple of months I've seen occasional lockups with the USB 
SSD. To see if it's the SSD, I switched to a mirrored USB-3 disk pair. I 
see the same lockups.

Power doesn't appear to be an issue - the USB SSD cable has a separate 
feed for power, and the hardware mirror has its own power supply.

My colocated 8 gig Raspberry Pi 4, which is running a kernel from the 
beginning of January wih two USB-3 attached drives with RAIDframe, hasn't 
had issues.

When the Pi locks up, everything gets stuck in biowait or tstile, and with 
both the SSD and the mirror, there's only one single "error reading fsbn" 
line on the console. dump & reboot lock the machine again, and only 
"reboot 0x4" actually reboots. It's as if the USB subsystem is 100% dead 
and never retries.

I've then moved the SSD to a Pi 3 with the same kernel, and I've been 
doing tons of disk I/O and lots of compiling with lots of swap use, and 
it is 100% fine.

Any thoughts or ideas about what might be different about USB on a Pi 4 
that might cause a read error to become fatal?

John Klos