Re: How to downgrade super speed device

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On Tue, 10 Feb 2015, Huang Rui wrote:

> On Mon, Feb 09, 2015 at 08:59:06PM -0500, Alan Stern wrote:
> > On Tue, 10 Feb 2015, Huang Rui wrote:
> > 
> > > On Mon, Feb 09, 2015 at 10:59:42AM -0500, Alan Stern wrote:
> > > > On Mon, 9 Feb 2015, Huang Rui wrote:
> > > > 
> > > > > Hi,
> > > > > 
> > > > > Do you have any trick to downgrade one USB3 capacity device from super
> > > > > speed mode to high speed mode on xhci port via host side?
> > > > 
> > > > Connect it to the host by a USB-2 cable.
> > > > 
> > > 
> > > If physical connection and port number are fixed, any idea on software
> > > side?
> > 
> > It may be possible to do this by disabling the port in some way (put it 
> > in some appropriate link state -- I don't know which one).  When the 
> > device sees the SuperSpeed connection is gone, it should reconnect at 
> > high speed.
> > 
> 
> You mean I should set link status of the special port on SS.Disabled
> state, not let it into Rx.Detect statue, right? Then the link can not
> go to Polling, and the device aborts this port and reconnect to the
> USB2 roothub port, is that right?

Yes, that is what I meant.

Alan Stern

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