Re: [PATCH] USB: serial: simple: narrow OWON match to avoid breaking VDS1022

[craig@xxxxxxxxxxx]

Hi all,

I apologize for the delay. I am sad to see that this change is causing
such a headache. Thank you all for handling this.

On Mon, 2026-08-17 at 17:35 +0800, Huang Wei wrote:
> Craig, was the intent of 4cc01410e1c1 to cover only the HDS200
> series,
> or the whole range of OWON scopes sharing this VID:PID?

The main intent was to cover the HDS200 series, however other OWON
devices seemed perfectly safe to cover, given most of them use this
same simple serial style IO. This assessment was just from analyzing
documentation, source, and bins.

This simple serial driver enumeration seemed like the right
convenience/abstraction, for most people, who don't want to learn how
USB endpoints, libusb, and explicit permission granting udev rules
work. Most distros already associate a convenient limited user group
dialout or uucp to the serial device for easy access and also easy
unbinding for libusb usage.

On Thu, 2026-10-15 at 10:54 +0800, Huang Wei wrote:
> And the point that the VDS1022 is a headless scope where
> the PC tool is the primary interface makes it clear it should stay
> unclaimed.

I think I am missing something, but why does being headless mean that a
serial interface shouldn't be bound? Or, is the primary issue just
breaking necessary user application? Again, my apologies in advance if
I am missing something.

To be completely fair, I didn't know the VDS1022 used a pure binary
over USB interface. However, I'm not sure that would have changed the
calculus, given it still LOOKS to be a simple two endpoint TX/RX serial
[raw] data interface. I hate that this change broken this application,
but wouldn't it reduce the complexity a bit for the Linux use case, by
removing the necessary udev rule, removing the runtime dep on
libusb.so, and simplifying libusb control code?

https://github.com/florentbr/OWON-VDS1022/blob/1.1.5-cf19/install-linux.sh#L337

>From a maintainability perspective, it would be unfortunate to have one
arbitrary subset of devices use serial and another use libusb.

On Thu, 2026-10-15 at 10:54 +0800, Huang Wei wrote:
> Craig - if you happen to know whether subclass 0 / protocol 0 holds
> across the HDS200 series and firmware versions, that would be a
> useful confirmation; the dump in your commit message is the only
> HDS200 data point I have.

Unfortunately, I do not know if other devices in the family maintain
this device 0 subclass and protocol, but I will try an older firmware
on the HDS272S and double check.

All the best,

Craig