Re: [Qemu-devel] Mixed USB 1.1 and USB 2.0 on the same port

[Erik Rull]

address@hidden wrote:
> > On 12/31/11 13:11, Erik Rull wrote:
> > > Hi all,
> > >
> > > how can I use a USB 1.1 device on the USB 2.0 bus? Currently the EHCI
> > > implementation complains that the device is mismatches the USB version.
> >
> > -readconfig docs/ich9-ehci-uhci.cfg
> >
> > cheers,
> >    Gerd
>
> Thanks for the hint.
>
> It looks better now. But some things are still a bit strange.
>
> Sequence:
> device_add usb-host,bus=ehci.0,hostbus=2,hostport=1.4
> Plug in a USB 2.0 printer
> (gets detected by the guest, printing is possible, no bluescreen, it just
> works)
> Remove the USB 2.0 printer
> Plug in a USB 1.1 dongle
> Gets detected, etc., fine
> Remove the USB 1.1 dongle
> Plug in the USB 2.0 printer again
> Guest complains now, that a USB 2.0 device was plugged into a USB 1.1 port
> =>  printer is now 1.1 and does not work as if EHCI is missing now
> =>  reboot guest, everything is fine again??
>
> Any idea what could have happened here?
> Same behavior when using a 2.0 USB key and the USB 1.1 dongle - also on
> other ports - the transfer rate is horrible after having removed the USB
> 1.1 device and reconnected the 2.0 device.
> Exchanging the two USB 2.0 devices on the same port without having the 1.1
> device plugged in is fine!
>
> Any hint what is wrong here would be great.
>
> Best regards,
>
> Erik

Additional Information:
This behavior is present on a Linux guest as well! After having removed the 
1.1 Dongle and plugged in the printer, the Linux guest detects the hardware 
via the UHCI kernel drivers and tells me to use a faster hub for max. 
performance.
It looks as if the speed downgrade by the 1.1 device cannot be reversed at 
runtime.

Best regards,

Erik