USB stall issues

From: Poul-Henning Kamp <phk_at_phk.freebsd.dk>
Date: Wed, 19 Aug 2026 11:20:17 UTC
I'm having some kind of trouble with USB-stalls on two devices:

* Canon DR1100C scanner (ugen)

Easiest to provoke, because it fails right out of the
gate and stalls long before any scanning takes place.

* GreaseWeazle (umodem)

Provoke by doing anything in the browser while a floppy is being read.

In both cases my reading of usbdump output is that the trouble starts with a STALL.

Who can give me some pointers to how I can debug this further ?


PS: These are not new problems, but they have only now bubbled up near
the top of my TODO list.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.