[Nut-upsuser] distinguishing identical multiple usbhid-ups devices

[Arjen de Korte]

> usbhid-ups is capable to distinguish devices from the Bus
> they are connected to, but as all are at the same hub the bus
> is the same. I'd like if usbhid-ups could distinguish them from
> the hubbed port they are plugged in.

This isn't possible/portable. Only the kernel is aware which physical port
the devices are attached to, but this information is lost when they are
handed off to the libusb layer. At that time, the only thing we have is an
enumerated value, which may (will) change each time you reconnect them. In
practice, this is so unstable that it can't be used.

The only thing that could possibly tell these devices apart (if they don't
have unique serial numbers), is the Bus. So unless you have multiple USB
busses on your system, you're limited to just one UPS of this type. We
can't fix this in NUT.

Best regards, Arjen
-- 
Eindhoven - The Netherlands
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