[SLOF] Keyboard not working when using XHCI as a USB host controller?

[Segher Boessenkool]

On Tue, Aug 04, 2015 at 10:09:33PM +0200, Thomas Huth wrote:
> On 04/08/15 18:56, Segher Boessenkool wrote:
> > On Tue, Aug 04, 2015 at 01:32:25PM +0200, Thomas Huth wrote:
> >> When I use the following command line to start a guest:
> >>
> >>  qemu-system-ppc64 -machine pseries,accel=kvm,usb=off \
> >> 	-device pci-ohci,id=usb,bus=pci.0,addr=0x2 \
> >> 	-device usb-kbd,id=input0 -nographic -vga none
> >>
> >> ... SLOF correctly discoveres a keyboard during USB scan:
> > 
> >> However, when I start with an XHCI (or EHCI) controller
> >> instead:
> >>
> >>  qemu-system-ppc64 -machine pseries,accel=kvm,usb=off \
> >> 	-device nec-usb-xhci,id=usb,bus=pci.0,addr=0x2 \
> >> 	-device usb-kbd,id=input0 -nographic -vga none
> >>
> >> ... SLOF does not discover any keyboard:
> > 
> > I don't know what those qemu options mean *exactly*, but I've
> > never heard of a keyboard that talks SS (HS are rare too, most
> > are FS these days) -- so the device should show up on a companion
> > controller, which should be OHCI as well.  What host controllers
> > were detected?
> 
> AFAIK for XHCI, you don't need these companion controllers anymore,
> e.g. see:
> https://en.wikipedia.org/wiki/Extensible_Host_Controller_Interface#Simplified_driver_architecture
> 
> So I think the keyboard should show up at the XHCI controller when I
> only specify the XHCI - but I am also not very experienced with XHCI
> yet, so I might also be wrong here.

Oh, right, close to zero experience with xhci here as well, but yeah I
remember something about translation upon translation on top of abstraction
on top of translation, and somehow it never quite works?  :-P

Either way, time for some tracing...  And remember the problem (or one
of the problems) could well be in qemu instead :-/


Segher