Re: [Qemu-devel] USB continuous reset / unplug cleanup not done properly

[Gerd Hoffmann]

  Hi,

> 1) Devices get resetted again and again on the host side and do not work
> properly on the guest side - they work fine on the host side outside qemu.

I see those too.  Not clear what is going on here.  usbfs requests seem
to get stuck now and then for not-yet known reasons.  Sometimes they
finish after a few seconds.  Sometimes they get stuck long enougth that
some timeout within the guest fires and the guest resets the device.

I see those with a F16 guest which polls the usb stick with
test-unit-ready requests.  Letting it run idle produces a ...

   usb 1-6: reset high speed USB device number 3 using ehci_hcd

... log line line in the guest now and then.  Tried to write a small
reproducer (tool constantly sending test-unit-ready via usbfs), but that
one works just fine without any hangs.

cheers,
  Gerd