USB serial device naming

[Nick Hibma]

>> Two things are needed:
>> 
>> 1) path to the device so you can distinguish two identical devices.
>> 
>> 2) map u3gN to cuaUX.Y
>> 
>> My problem is the latter:
>> 
>> Processing event '+u3g0 vendor=0x0af0 product=0x7601 devclass=0xff
>> devsubclass=0xff sernum="" release=0x0000 intclass=0xff intsubclass=0xff
>> at port=2 interface=0 vendor=0x0af0 product=0x7601 devclass=0xff
>> devsubclass=0xff sernum="" release=0x0000 intclass=0xff intsubclass=0xff
>> on uhub1' Pushing table
> 
> Hi,
> 
>> How do I get to the cuaU10.0 device here? As far as I can see there is no
>> way to do this.
> 
> I think we should use the following format:
> 
> cuaU<bus>.<addr>.<iface>[.<sub_unit>]
> 
> Then you can match by ugenX.Y unit. Possibly we could add this information to 
> the processing event.

Yes. We need a mapping from vendor/product/rev -> /dev/ entry and from location -> /dev/ entry. Adding this cuaU<bus>.<addr>.<iface> string (not the absence of the sub_unit) to the event would resolve both issues 1) and 2).

/me starts handing out paint and pencils for the bike shed painting to come...

>> The main problem is the strange way the minor number is assigned to the
>> cuaU device. But having the major and minor numbers for the cuaU device
>> per u3g instance would be sufficient. Through a sysctl for example, or as
>> extra information in the attach.
> 
> You mean in the device name, not in the inode?

Device name, right. The mknod stuff is too old to be wrong...

> Please send a patch for review.

Will do in the next two weeks.

Nick