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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Wed, 09 Oct 2013 10:55:39 +0200
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Subject: Re: [Qemu-devel] [PATCH 03/13] usb-host-libusb: Detach kernel
	drivers earlier
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To: Hans de Goede <hdegoede@redhat.com>
Cc: qemu-devel@nongnu.org

On Di, 2013-10-08 at 21:58 +0200, Hans de Goede wrote:
> If we detach the kernel drivers on the first set_config, then they will
> be still attached when the device gets its initial reset. Causing the drivers
> to re-initialize the device after the reset, dirtying the device state.

> @@ -1051,7 +1055,6 @@ static void usb_host_set_config(USBHostDevice *s, int config, USBPacket *p)
>      trace_usb_host_set_config(s->bus_num, s->addr, config);
>  
>      usb_host_release_interfaces(s);
> -    usb_host_detach_kernel(s);
>      rc = libusb_set_configuration(s->dh, config);
>      if (rc != 0) {
>          usb_host_libusb_error("libusb_set_configuration", rc);

Sure we can safely remove the detach_kernel here?

Assuming we have a device with multiple configurations, each
configuration has a different set of interfaces, guest switches from one
config to another.  Do we correctly unbind kernel / claim interfaces
then?

Handling this correctly was the reason to do the kernel unbind in
response to the guests set_config instead of host_open btw, although I
can see the issues the late unbind introduces.

cheers,
  Gerd