On Sat, 7 Feb 2004, Bernd Porr wrote:

> Hi Alan,
> 
> let's say: it works with VIA as bad as before. ;-) The UHCI driver 
> itself works -- if the ehci driver is/was loaded (before).

That's good to hear.

> If I only load the UHCI driver all external devices get no power at all 
> (measured with a meter).
> 
> To get power to the external bus I have to first load both drivers: ehci 
> and uhci. When I remove the ehci driver the power is still on.
> 
> I discussed this problem with Dave a while ago and we agreed that time 
> that we leave the problem unresolved. Maybe now it's time to fix it with 
> this patch as well?

That sounds like it involves some weird detail of how the board manages 
handing off non-high-speed devices to the companion controller.  For 
instance, maybe the PCI interface to the EHCI controller has to be enabled 
before the UHCI controller can access the USB bus.  Or maybe power to the 
bus is totally under the control of the EHCI hardware and not the UHCI 
hardware.

I'm not sure where to start looking, but I suspect that the fix will be 
found somewhere other than in the UHCI driver.  Anyway, it probably 
deserves its own patch since it's really a separate problem from the one 
this patch was designed to fix.

Alan Stern



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