> If it was a whole new driver, would there be any difficulty with attaching
> to either a BOT device or a UAS device, depending on the device's subclass
> code? Would the correct mass-storage driver get invoked somehow?
Absolutely not.
Each interface and each alternative of the interface, maps to a USBD, given
the interface class, subclass and protocol. The usb-core will either perform
a dynamic mapping by advertising the triple to each USBD and then whomever
"returned" the highest weight gets to handle the IF (less preferable), or
the more preferable, each USBD declares the IF class, subclass and protocol
it handles and its relative weight.
Thus, when the device presents IF0 alternative 0 as BOT (BBB) with two EPs,
and IF0 alternative 1 as UAS with 4 EPs, if there is a UAS USBD in the system,
the UAS IF0:1 should be preferred over the BOT one, IF0:0 (USBD is the BOT driver,
a la "usb-storage").
An abstraction layer (usb-core) sitting between the HCD and the USBD would then correctly
configure the device and interface and hand off the pipes to the USBD (in this case
implementing UAS).
Luben
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