Re: [PATCH v7 10/14] usb: otg: add hcd companion support

[Alan Stern]

On Wed, 11 May 2016, Roger Quadros wrote:

> > What I mean is if you have 2 EHCI controllers with 2 companion 
> > controllers, don't you need to know which companion goes with which EHCI 
> > controller? Just like you do for the otg-controller property.
> > 
> 
> That is a very good point. I'm not very sure and it seems that current code won't work
> with multiple EHCI + companion instances.
> 
> Alan, does USB core even know which EHCI and OHCI are linked to the same port
> or the handoff is software transparent?

The core knows.  It doesn't use the information for a whole lot of 
things, but it does use it in a couple of places.  Search for 
"companion" in core/hcd-pci.c and you'll see.

Alan Stern