RE: FW: Staging usb_gadget_register driver, 2.6.35

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> > > > > 1) cannot have two gadget peripheral controllers as modules in a >
given
> > > > > > kernel
> > > > 
> > > > > True.
> > > > 
> > > > Is this behavior by design or accident?
> > 
> > > Design.  The USB specs only allow one upstream
> > > port, meaning one USB peripheral controller in
> > > any USB-certified device.
> > 
> > > So why would we bother trying to support two, if
> > > that's contrary to the standards we follow??
> > 
> > The USB spec allows one upstream facing port, but that does not
necessarily
> > mean one USB peripheral controller per device. There are many mobile
devices
> > on the marketing that have two physical controllers connected to the
same
> > upstream port through a USB switch. These devices are USB certified, so
by
> > definition of the certification this implementation is not contrary to
the
> > standards we follow.
> 

> Also, as another example, you could have two physical USB peripheral
> controllers on an SoC, with one of them meant for inter-chip
> connections with a host on the same PCB, and the other meant to be
> exposed to the outside world as the upstream facing port.

This is another good example. It seems the loadable module controller model
might not work as well here though.


---------------------------------------------------------------
This message and any attachments may contain Cypress (or its
subsidiaries) confidential information. If it has been received
in error, please advise the sender and immediately delete this
message.
---------------------------------------------------------------

--
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


[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux