[libhid-discuss] how to select Report ID?

[Charles Lepple]

On Mar 11, 2010, at 6:32 PM, Christopher Boger wrote:

> I have a device with multiple Report IDs. Each of the Report IDs is  
> associated with the same Usage Page and Usage number. So, basically  
> I have one path. How exactly do I select the Report ID? It looks  
> like when I write a report using the path, it shows a report ID in  
> the TRACE printout, but basically it’s choosing the first report ID  
> that matches this path. How do I select others? Is this a limitation  
> of libhid? Or, am I not getting something?

Can you post a dump of the descriptor?

It is probably a limitation of the library, but all of the HID class  
devices I have seen use different paths. The whole point of the Usage  
numbers is to uniquely identify values in a collection. In the case of  
multiple identical Usage values that exist in different collections,  
the Usage of the parent collection (in libhid, the preceding  
element(s) of the "usage path") is used to disambiguate the Usages.