On Wednesday 27 April 2005 12:16 pm, Alan Stern wrote:
> On Wed, 27 Apr 2005, David Brownell wrote:

> 
> > > > Note that both EHCI and OHCI already _have_ such logic in the hub_status
> > > > code ... but it wasn't sufficient before.  There are a LOT of paths 
> > > > through
> > > > usbcore and HCDs on which things will trip up.
> > > 
> > > Guess I'm used to UHCI, where things are simpler.
> > 
> > I'm not sure it's a case of things being simpler.  I was testing a
> > few dozen different configurations, and not all of them had those
> > wierd cases.  There's nothing fundamentally different about UHCI;
> > it could have those same configurations.
> 
> Can you remember any particular configurations or code paths that were 
> troublesome?  If similar things exist in UHCI then I need to know about 
> them.  As far as I'm aware there are no outstanding problems of this 
> sort.

I tested a lot of things, all of which need to work in combinations...

 - Remote wakeup
 - Selective suspend of the root hub (and children)
 - Selective suspend of the HCD (and children)
 - System sleep when either HCD or root hub is already suspended
 - Multiple system sleep states:  S1 or S3, S4, swsusp/reboot, etc
 - Different BIOS options (with/without USB keyboard support)
 - Controllers with/without PCI PM support
 - PCI cards vs motherboard controllers
 - EHCI active vs not
 - ...

It was a bit too common that something would only fail in some
particular configuration(s) but work well otherwise. 

- Dave



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