[PATCH v2 2/2] USB: doc: Binding document for ehci-platform driver

Alan Stern stern at rowland.harvard.edu
Wed Oct 24 15:30:43 EDT 2012

On Wed, 24 Oct 2012, Mitch Bradley wrote:

> >> Ah, now I'm starting to get the picture.
> >>
> >> 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.

Unfortunately that's not saying very much.  The EHCI spec describes
only PCI-based controllers.  Every other sort does require something

> 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.

While I haven't checked in detail, it seems quite likely that this 
would not work with some of the devices that have "usb-ehci" listed in 
their compatible values.

Alan Stern

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