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

[Lin Ma <lma@suse.com>]

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 <lma@suse.com>
>> ---
>>   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;
>>
>
>