Re: [Qemu-devel] [PATCH] Introduce new "no_guest_reset" parameter for usb-host device (fwd)

[Gerd Hoffmann]

On Thu, Dec 27, 2018 at 02:19:09PM -0800, Alexander Kappner wrote:
> 
> Resending; forgot to CC maintainer.

Now the list mail address is wrong (.com instead of .org).

> 1) Guest recognizes new device, sends reset to emulated USB host
> 2) QEMU's USB host sends reset to host kernel
> 3) Host kernel resets device
> 4) After reset, host kernel determines that some part of the device descriptor
> has changed ("device firmware changed" in dmesg), so host kernel decides to
> re-enumerate the device.

Not sure this is actually the reason ...

> 5) Re-enumeration causes QEMU to disconnect and reconnect the device in the
> guest.
> 6) goto 1)
> 
> Here's from the host kernel (note the "device firmware changed" lines")
> 
> [3677704.473050] usb 1-1.3: new high-speed USB device number 53 using ehci-pci
> [3677704.555594] usb 1-1.3: New USB device found, idVendor=05ac, 
> idProduct=12a8, bcdDevice=11.08
> [3677704.555599] usb 1-1.3: New USB device strings: Mfr=1, Product=2, 
> SerialNumber=3
> [3677704.555602] usb 1-1.3: Product: iPhone
> [3677704.555605] usb 1-1.3: Manufacturer: Apple Inc.
> [3677704.555607] usb 1-1.3: SerialNumber: [[removed]]
> [3677709.401040] usb 1-1.3: reset high-speed USB device number 53 using 
> ehci-pci
> [3677709.479486] usb 1-1.3: device firmware changed

.. here it is ...

> [3677709.479842] usb 1-1.3: USB disconnect, device number 53
> [3677709.546039] usb 1-1.3: new high-speed USB device number 54 using ehci-pci
> [3677709.627471] usb 1-1.3: New USB device found, idVendor=05ac, 
> idProduct=12a8, bcdDevice=11.08
> [3677709.627476] usb 1-1.3: New USB device strings: Mfr=1, Product=2, 
> SerialNumber=3
> [3677709.627479] usb 1-1.3: Product: iPhone
> [3677709.627481] usb 1-1.3: Manufacturer: Apple Inc.
> [3677709.627483] usb 1-1.3: SerialNumber: [[removed]]
> [3677762.320044] usb 1-1.3: reset high-speed USB device number 54 using 
> ehci-pci
> [3677762.615630] usb 1-1.3: USB disconnect, device number 54

... but on the second cycle this is missing but there is still a disconnect.

Could be the phone actually disconnects.

> introduced for the usb-host device. I can confirm that the configuration
> described above (iPhone XS + Mojave guest) works flawlessly with
> no_guest_reset=True specified.

Can you make this "guest-reset=false"?  Otherwise the patch looks fine.

thanks,
  Gerd