RPi 4B USB 3 support appears to still be broken in 13.0-RELEASE

[Robert Clausecker]

Greetings!

Last time I experimented with ZFS on the RPi 4B, I noticed that
there is a strange problem when attaching the zpool via USB 3 as
opposed to USB 2.  When doing that, mounting root fails with
IO errors like these:

(da0:umass-sim0:0:0:0): READ(10). CDB: 28 00 03 c1 b9 65 00 00 07 00 
(da0:umass-sim0:0:0:0): CAM status: CCB request completed with an error
(da0:umass-sim0:0:0:0): Retrying command, 3 more tries remain
(da0:umass-sim0:0:0:0): READ(10). CDB: 28 00 03 c1 b9 65 00 00 07 00 
(da0:umass-sim0:0:0:0): CAM status: CCB request completed with an error
(da0:umass-sim0:0:0:0): Retrying command, 2 more tries remain

Attaching the boot disk through USB 2 instead works.  Likewise,
using USB 3 with a UFS root file system works (and in fact ran fine
in a development system for months).  I do not understand this.

I had previously reported this issue as PR 249520:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=249520

There's some stuff about UEFI booting in there which you can ignore.
The same problem also appears when booting via U-Boot.

Now what surprises me is that this issue still occurs with
FreeBSD 13.0-RELEASE.  So whatever fixes had been performed
did not seem to address the underlying problem at all.

Is there any workaround or solution (except for ditching root
on ZFS which would be rather painful for my use case?)

Yours,
Robert Clausecker

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