Re: [Qemu-devel] [PATCH] Re-attach usb device to kernel while usb_host_open fails

[Lin Ma]

在 2015年06月23日 16:29, Gonglei 写道:
> On 2015/6/23 12:24, Lin Ma wrote:
> > Signed-off-by: Lin Ma <address@hidden>
> > ---
> >   hw/usb/host-libusb.c | 5 +++++
> >   1 file changed, 5 insertions(+)
> >
> > diff --git a/hw/usb/host-libusb.c b/hw/usb/host-libusb.c
> > index 10f4735..7258c4d 100644
> > --- a/hw/usb/host-libusb.c
> > +++ b/hw/usb/host-libusb.c
> > @@ -888,6 +888,11 @@ static int usb_host_open(USBHostDevice *s, libusb_device 
> > *dev)
> >   fail:
> >       trace_usb_host_open_failure(bus_num, addr);
> >       if (s->dh != NULL) {
> > +        qemu_remove_exit_notifier(&s->exit);
> > +        QTAILQ_REMOVE(&hostdevs, s, next);
> This change will cause a regression. For example, if an usb device's
> (assume that it's usb1.0 device) speed does not match the ehci adapter,
> then then invoking usb_host_open failed. if somebody changes the usb
> device to an usb 2.0 device, it will not auto check because the device has
> removed from the global hostdevs list.
>
> So I think we don't need  do the above operations.
In this situation, in my opinion, User should perform device_add to add 
the device again, Then the device will be added
to hostdevs list and can be auto checked again, right?

In addition, The usb_host_open will be performed 3 times until 
's->errcount >= 3' while invoking usb_host_open failed.
If the usb device isn't removed from hostdevs list, It will be detached 
& re-attached 3 times.


Thanks,
Lin
> > +        usb_host_release_interfaces(s);
> > +        libusb_reset_device(s->dh);
> > +        usb_host_attach_kernel(s);
> >           libusb_close(s->dh);
> >           s->dh = NULL;
> >           s->dev = NULL;