[PATCH 13/15] USB: ehci: make orion and mxc bus glues coexist

[Alan Stern]

On Tue, 22 Jan 2013, Manjunath Goudar wrote:

> > >  I think we can actually
> > > get the same results by turning the Kconfig logic around and making
> > > the platform glue drivers 'select USB_EHCI_HCD' than depending on
> > > it.
> >
> > That's a good idea.  The Kconfig changes would have to be done
> > carefully to make sure that the dependency on USB_ARCH_HAS_EHCI still
> > applies to all the platform drivers.
> >
> > Manjunath, would you like to send a patch to do this?
> >
> > Alan Stern
> >
> > Ya sure,could you explain little bit  briefly about the Kconfig changes.

Suppose you do exactly what Arnd proposed: add "select USB_EHCI_HCD" to
the Kconfig entries for each of the platform glue drivers.  Then
consider what would happen in a build where USB_ARCH_HAS_EHCI is "n"
but one of those glue drivers is enabled.  There would be conflicting
requirements on USB_EHCI_HCD: The new "select" would force it to be on,
but the existing "depends on USB && USB_ARCH_HAS_EHCI" would force it
to be off.  The build would fail.

In order to prevent this, you have to make sure that each glue driver
depends on USB_ARCH_HAS_EHCI.  A simple way to do this is to surround
the Kconfig entries for those drivers with "if USB && 
USB_ARCH_HAS_EHCI" ... "endif".

Come to think of it, the "if USB" part really should protect the entire 
file.

Alan Stern