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[Qemu-devel] Re: USB-OHCI / UHCI: Isochronous transfer not working on Li
[Qemu-devel] Re: USB-OHCI / UHCI: Isochronous transfer not working on Linux host
Thu, 11 Dec 2008 10:46:43 -0800
Thunderbird 188.8.131.52 (X11/20080723)
Sorry for delay in replying.
(CCing Mark Burkley who recently posted EHCI patches)
Thomas Bandelier wrote:
Most USB 2.0 devices should work just fine with the current UHCI code.
Including isochronous transfers. While developing new UHCI
implementation I was testing it with several 2.0 devices like USB
storage devices and MS Webcam. Webcam uses isoc transfers and worked
However since UHCI does not do 2.0 rates USB bandwidth is much lower in
Hi Arnon, Max, Pierre,
Arnon, Thanks for your feedback on this point.
As we need to manage several USB 2.0 devices in our environment, we are
going to work on this aspect. We are very motivated to make it work.
Do you (Max and/or Arnon) have any idea of what should be done /
reworked in order to support USB 2.0 devices and especially isochronous
transfers in QEMU?
We would prefer keeping OHCI implementation, but do you think we should
switch to UHCI? Or maybe EHCI?
Ideally we need to switch to EHCI in order to support high USB2.0
speeds. Not too long ago Mark posted a EHCI implementation (I have not
had much luck with it and XP yet though).
If we can keep OHCI, what should we begin to do in order to debug
current QEMU OHCI implementation? Same question for the other
controllers if we have to switch.
Otherwise if you're ok with lower BW then UHCI should work fine.