On Thu, 24 May 2007, David Brownell wrote:
> On Thursday 24 May 2007, Alan Stern wrote:
> > Dave:
> >
> > In this section from usb_new_device():
> >
> > if (!is_targeted(udev)) {
> >
> > /* Maybe it can talk to us, though we can't talk to it.
> > * (Includes HNP test device.)
> > */
> > if (udev->bus->b_hnp_enable || udev->bus->is_b_host) {
> > err = __usb_port_suspend(udev, udev->bus->otg_port);
> > if (err < 0)
> > dev_dbg(&udev->dev, "HNP fail, %d\n", err);
> > }
> >
> > Is there any reason to call __usb_port_suspend() rather than
> > usb_port_suspend()?
>
> Maybe not any more.
Okay, I'll change it. It will allow the removal of one layer of
nesting.
> > After all, an OTG device is required to have no
> > more than one USB connection, so the port number would always be equal
> > to udev->portnum and to 1.
>
> Not true. It's perfectly legit for a host to have multiple host
> ports, with only one of them being OTG-capable.
Really? What about section 3.2 in the OTG spec, where it says that an
On-The-Go device must include:
one, and only one connection: a Micro-AB receptacle.
Has this been superseded? Or do people simply ignore it?
> Not uncommon either;
> it's a simple implementation strategy (combining existing silicon IP
> with an OTG engine), and board designers find serial busses like USB
> are handy as a way to integrate various devices ... simple to route
> on the boards, only two pins, and so forth. It's not just a way to
> connect external devices.
Alan Stern
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