On Thu, 15 Apr 2010, Luben Tuikov wrote: > > 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. Where did you get this idea? Not from reading the code -- this looks more like how you _imagine_ it might work than how it really does work. > 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). No. usbcore does not configure interfaces. That is left up to the individual drivers. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
