Re: [gentoo-user] printer uses UHCI instead of EHCI. Why?

[Jens Krahe]

Am Sonntag, 17. Februar 2008 schrieb Volker Armin Hemmann:
> On Sonntag, 17. Februar 2008, Jens Krahe wrote:
> > Am Samstag, 16. Februar 2008 schrieb Andrew Gaydenko:
> > > Ehci module is loaded, all MB USB ports are USB 2 ports, printer is
> > > "USB 2 (Full Speed)" printer.
> >
> > And there is nothing wrong. EHCI handles only the High Speed mode of
> > USB2! Low and Full Speed are still handled by UHCI/OHCI.
>
> you are wrong, kernel with ehci only:
>
> [   31.592651] usb 1-3.1: new low speed USB device using ehci_hcd and
> address 4

And the device works?

However, I refer to Universal Serial Bus EHCI Specification [1]
on page 3:
"A USB 2.0 Host Controller includes one high-speed mode host controller and 0 
or more USB 1.1 host controllers (see Figure 1-2). The high-speed host 
controller implements an EHCI interface. It is used for all high-speed 
communications to high-speed-mode devices connected to the root ports of the 
USB 2.0 host controller. This specification allows communications to Full- 
and Low-speed devices connected to the root ports of the USB 2.0 host 
controller to be provided by companion USB 1.1 host controllers."

and on page 4:
"High-speed devices are always routed to and controlled by the EHCI host 
controller (eHC). When running and configured, the eHC is the default owner 
of all the root ports. The eHC and its driver initially detect all device 
attaches. It has additional control bits visible in each port register to 
manage the routing logic. For example: if the attached device is not a 
high-speed device, the eHC driver releases ownership of the port (and thus 
control of the device) to a companion host controller. For that port, 
enumeration starts over from the initial attach detect point and the device 
is enumerated under the cHC. Otherwise, the eHC retains ownership of the port 
and the device completes enumeration under the eHC."

Regards
Jens

[1] http://www.intel.com/technology/usb/download/ehci-r10.pdf
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