[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?

Ah, I see what happened. libhid has a bug in which the Usages for  
ranges are not printed properly.

[I think I accidentally dropped that message, but the list has a limit  
of 40KB including attachments. I would recommend against sending HTML,  
as it tends to hit that limit quickly.]

Here's an excerpt of the dump you sent:

parse tree of HIDInterface 002/037[2]:
   path: 0xff000001.0xff000001; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0xff000001; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80
   path: 0xff000001.0x00000000; type: 0x80

If a path ends in 0x00000000, it is probably being printed  
incorrectly. There is a script in SVN which decodes a hex dump of the  
HID report descriptor. Not sure if I have described how that script  
works on the list, but if you have trouble, send the descriptor hex  
dump from the test_libhid program.