On Tue, 30 Nov 2010, Sarah Sharp wrote:
> On Tue, Nov 30, 2010 at 11:06:21AM -0500, Alan Stern wrote:
> > On Mon, 29 Nov 2010, Sarah Sharp wrote:
> > > @@ -1234,6 +1252,14 @@ struct xhci_hcd {
> > > u32 suspended_ports[8]; /* which ports are
> > > suspended */
> > > unsigned long resume_done[MAX_HC_PORTS];
> > > + /* Is each xHCI roothub port a USB 3.0, USB 2.0, or USB 1.1 port? */
> >
> > This comment is unclear; the port_array field doesn't answer the
> > question asked in the comment. Furthermore, none of the ports can be
> > USB 1.1 -- they all have to be USB-2 or USB-3.
>
> Ok, on closer look at this, the comment is correct. Each port_array
> element is taken from the Major Revision field in the Extended
> Capabilities, so it can be 0x1, 0x2, or 0x3. If the port shows up twice
> in the Extended Capabilities registers (it could happen, although it
> should be caught by the USB-IF compliance tests), then that element is
> set to -1 and the port is ignored. Probably the port should be
> disabled, but the code doesn't do that.
Ah -- I misread the code. Instead of making port_array a pointer, why
not make it an array of some maximum fixed length?
Does xHCI allow an implementation to use separate port registers for
high speed vs. full/low speed?
Alan Stern
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