Re: USB EHCI Problem with Low Speed Devices on kernel 2.6.11+

[Randy.Dunlap]

On Mon, 29 Aug 2005, Jan De Luyck wrote:

> On Monday 29 August 2005 01:16, James Courtier-Dutton wrote:
> > Dominik Wezel wrote:
> > > Problem
> > > =======
> > > When turning on the laptop and during POST and GrUB loading, all ports
> > > on the hub are enabled.  During the USB initialization phase, when the
> > > hub is detected, shortly all ports become disabled, then turn on again
> > > (uhci_hcd detects the lo-speed ports).  Upon initialization of ehci_hcd
> > > however, the ports are disconnected again (for good):
> >
> > Use uhci_hcd or ehci_hcd, but never both at the same time.
> > ehci_hcd will work with all lo-speed ports, so uhci_hcd is then no needed.
>
> This seems to be in contrast with what hotplug does automatically: it loads
> both ehci_hcd and uhci_hcd here. If I don't load uhci_hcd, lo-speed devices
> do not work.

Right.  EHCI is high-speed only.  It needs a companion controller
and driver for low- and full-speed devices.

-- 
~Randy
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/