faking or posing as a specific USB ID?

[Jani Monoses <jani@ubuntu.com>]

Hello,

the lkml is probably a better list for this question but there may be a 
udev answer to it.

The problem I am trying to find the most elegant solution for is the 
following: given a certain driver that supports USB device AAAA:BBBB try 
to see if it works with new device CCCC:DDDD without rebuilding (or 
hexediting :) the module by somehow asking it to treat the new device as 
if it were AAAA:BBBB.

In particular, quickly trying out a new webcam by asking/duping various 
v4l webcam drivers to see it as another ID they already handle well, and
when one is found only then modifying the sources to add it to the list 
of supported devices. There are quite a few devices that have the same 
chip combinations inside and this method would allow easier testing for 
less technical people, and would also save time for those who can build 
kernels.

This may not be possible with the current kernel, as drivers only look 
for devices hardcoded in their .initdata sections. While  some can be 
told via a new_id sysfs attribute to add a new ID dynamically to their
supported list, webcams and probably other families of devices would 
need to specify extra parameters (ex: bridge and img sensor tuple) 
besides the ID.

Does udev have some way of faking insertion events or altering an event 
coming from the kernel and sending it back that way? A rule that says in 
effect, rename USB ID AAAA:BBBB to CCCC:DDDD ?

If not, the the ID matching code in the kernel is the one I think could 
be told via a syfs atribute similar to new_id.

thanks for any comments or pointers you may have

Jani