Re: [RFC]Is usb port number fixed?

From: Alan Stern
Date: Sat Apr 21 2012 - 13:23:29 EST

On Sat, 21 Apr 2012, Wang YanQing wrote:

> On Fri, Apr 20, 2012 at 08:32:37PM -0400, Alan Stern wrote:
> > In this particular case, it is guaranteed that the left USB port will
> > always be numbered as X-1.1:1.0 and the right port as X-1.2:1.0, where
> > the number X may change from one boot to another. But the -1.1:1.0 and
> > -1.2:1.0 parts will always be the same.
> >
> > This is because X is the bus number, which is allowed to change. The
> > -1.1:1.0 and -1.2:1.0 values are port, configuration, and interface
> > numbers. They will never change, because they come from the hardware.
> Yes, configuration and interface come from the hardware,
> but I don't know where the port come from, at least I don't think the port
> comes from the same hardware with the configuration and interface, do you
> mean port come from the hub?

Yes, it does.

Alan Stern

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