device filtering support

[Travis]

On 2/7/2012 4:36 PM, Segher Boessenkool wrote:
>>>> Right now I am more inclined to Segher's compromised
>>>> proposal of give user the option of using filter to reduce
>>>> unnecessary traffic (please refer to my previous reply).
>>>
>>> Yeah, I'm pretty sure it's possible to convert VID/PID to GUIDs, or
>>> to determine the VID/PID without actually querying the device;
>>> after all, the VID & PID are encoded in the device instance path.
>>
>> My thought is that GUID can be a filter for Windows.
>
> That will make your code Windows-only.  If you also do not implement
> the VID/PID filter, you cannot build any code written on another
> platform; if you do implement it but stub it out, it will run but
> just as insanely slow as it does now; and if you have the VID/PID
> filter implemented in such a way that it does in fact reduce traffic
> as it should, then what do you need a filter on GUID for?
>
> I see no up side to this idea, sorry.
>

The device class/subclass and protocol are cached right in the registry 
(CompatibleIDs).  You would not need a GUID, but it would work better on 
windows because it would allow users to search for a specific class of 
vendor devices. IE: a group of their own devices.

Regards,
Travis