[Spice-devel] [PATCH 0/5] RFC: Support UsbDk backend

[Dmitry Fleytman]

Hi Christophe,

Thanks for the review. See below.


> On May 28, 2015, at 19:03 PM, Christophe Fergeau <cfergeau at redhat.com> wrote:
> 
> On Thu, May 28, 2015 at 01:23:59PM +0300, Kirill Moizik wrote:
> Hey,
> 
>> This set of patches add UsbDk backend support to spice-gtk. This series currently cannot be applied since it require next patches series in libusb 
>> http://marc.info/?l=libusb-devel&m=142532078226137&w=2 .
>> We are waiting for this patches to be commited to libusb soon and then this series can be applied.
> 
> What happens when spice-gtk is built/run against a libusb version
> without the patches? Is there a way to detect this situation at runtime?
> Or do we need a configure check on the libusb version which is being
> used in order to disable usbdk if it's too old?

Since UsbDk patches introduce no changes to libusb interface I see no way to detect this in runtime.
The same problem exists for the compile time verification - libusb, even withUsbDk patches, may be
compiled without UsbDk support, so checks based on libusb version will be not trusted.

Surely it is a good idea to verify consistency of configuration between spice-gtk and libusb,
so any idea of how to do it in a robust way is highly welcomed.

> 
> 
>> 
>> Dmitry Fleytman (3):
>>  build: add build option for non-winusb redirection backends
>>  usbdk: Add UsbDk hider interface wrapper
>>  usb-device-manager: Configure UsbDk hiding rules on auto-redirection
>> 
>> Pavel Gurvich (2):
>>  windows: fix device matching for non-WinUSB configurations
>>  usbdk: make backend selection dynamic
> 
> As far as I understand, this series addresses the automatic redirection
> of devices when they are plugged in. What happens for already plugged
> devices that the user may want to redirect (eg the built-in webcam in
> laptops)? On linux you can go to the USB Device Selection menu, and
> manually redirect a device from there. Is it already working on Windows?

AFAICT there should be no difference between usbclerk and UsbDk behaviour for auto-redirection.

> 
> Last but not least, I think you mentioned some freeze occurring when
> redirecting some devices, and said it would be best to fix it in
> spice-gtk. Can you give more details as to when this freezing occurs,
> where exactly in the code this occurs (eg spice-gtk method name, and
> libusb function which freezes) ? Do you need help with fixing that?


Yes, the issue is libusb_open/libsub_close functions take 2-3 seconds with UsbDk because they now reset USB device internally. 
With current patches spice-gtk freezes for that period of time which is a slight problem from UX point of view.

Since the issue is spice-gtk specific, i.e. it is not relevant for non-interactive or CLI applications, we believe it should be fixed in spice-gtk.
Our current idea is to spawn separate thread(s) for start/stop redirection operations to allow spice-gtk process user input and behave smoothly.

Of course we will be glad if you help deal with that issue. What would you suggest?


Thanks,
Dmitry

> 
> Christophe