On Mon, 12 Mar 2007, Terry Moore wrote:
> Your descriptors are a little confusing.  The VID/PID don't match what I 
> thought were the VID/PID that was problematic, 0x050D/0x0121.

That's right, I've not found anyone with that product to test yet, we've 
only looked at other aue(4) devices.

> One of the difficult things about USB is that it really demands a 
> globally-aware probe mechanism that can resolve multiple possible matches in 
> favor of the "most specific".  Windows and Mac OS X both have this.  When 
> selecting a driver, each match is given a score, and the match with the best 
> score is used. (Windows only makes this decision the first time the device is 
> seen, and then remembers a vid/pid/rev/{location|serialnum} string, which is 
> used the next time the device appears.  Mac OS X simply repeats the vote 
> every enumeration.
>
> It's going to be hard to make USB enumeration work nicely if the system can 
> only use a simple sequential probe-until-claimed paradigm.

As I understand it, we do rank them by specificity. UMATCH_VENDOR_PRODUCT 
(as used by aue) is higher than UMATCH_IFACECLASS_IFACESUBCLASS_IFACEPROTO 
as used by ubt.

/* Match codes. */
#define UMATCH_HIGHEST                                  15
/* First five codes is for a whole device. */
#define UMATCH_VENDOR_PRODUCT_REV                       14
#define UMATCH_VENDOR_PRODUCT                           13
#define UMATCH_VENDOR_DEVCLASS_DEVPROTO                 12
#define UMATCH_DEVCLASS_DEVSUBCLASS_DEVPROTO            11
#define UMATCH_DEVCLASS_DEVSUBCLASS                     10
/* Next six codes are for interfaces. */
#define UMATCH_VENDOR_PRODUCT_REV_CONF_IFACE             9
#define UMATCH_VENDOR_PRODUCT_CONF_IFACE                 8
#define UMATCH_VENDOR_IFACESUBCLASS_IFACEPROTO           7
#define UMATCH_VENDOR_IFACESUBCLASS                      6
#define UMATCH_IFACECLASS_IFACESUBCLASS_IFACEPROTO       5
#define UMATCH_IFACECLASS_IFACESUBCLASS                  4
#define UMATCH_IFACECLASS                                3
#define UMATCH_IFACECLASS_GENERIC                        2
/* Generic driver */
#define UMATCH_GENERIC                                   1
/* No match */
#define UMATCH_NONE                                      0

-- 
Stephen