Re: [linux-usb-devel] [PATCH] : Allow embedded developers USB options normally reserved for OTG

[David Brownell]

On Wednesday 02 January 2008, Mike Frysinger wrote:
> > >
> > > Allow embedded developers to turn support for USB Hubs off even if they have a
> > > full root hub. This saves the overhead (RAM and Flash size).
> >
> > ISTR that it won't save very much code though ... the Linux USB
> > stack structures all its enumeration logic around hubs.
> 
> perhaps the code size is arguable as to whether it really matters.
> the reason we want it is that we have a USB host controller that will
> not work with USB hubs, so we want to make sure the system does not
> attempt such things.  (yes, such a USB host controller is retarded,
> but the decision was out of our hands.)

Well, it won't work with *external* hubs.  Root hubs are a different
story.  :)

I think that's one of a class of decisions sometimes made by folk
who need to conserve silicon real estate.  Supporting external hubs
has always been optional for OTG systems.

- Dave


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