On Thu, 25 Oct 2012, Sebastian Andrzej Siewior wrote: > On Wed, Oct 24, 2012 at 08:55:27AM -1000, Mitch Bradley wrote: > > >> So by listing "usb-ehci" in its device ID table, a driver would > > >> essentially be saying that it can handle _all_ USB EHCI controllers. > > > > > > Actually, it means that the driver can handle at least USB EHCI > > controllers that are 100% compatible with the EHCI spec (requiring > > nothing extra). The driver might be able to handle almost-compatible > > controllers, possibly with the help of additional properties. > > > > If a DT node lists "usb-ehci" as a "fallback", it's not guaranteed that > > a given version of that driver will work, but it's worth a try in the > > event that no more-specific driver is matched. > > Not sure fallback is a good term here. The of parses the compatible from left > to right. If the device specific entry is not found (in the driver) then end > up with usb-ehci. If we need a quirk later on we add the device specific entry > to the driver (which will match before usb-ehci is found) and we could use > this entry to apply the quirk. That way you can apply quirks without touch the > firmware / device tree. What happens if the drivers get probed in the wrong order? That is, if ehci-platform gets probed before ehci-spear (or whatever)? 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
