Re: Bug report: 045e:0721 Microsoft LifeCam NX-3000 not detected

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Hi Alan and Jürgen,

On Friday 30 August 2013 11:02:15 Alan Stern wrote:
> On Fri, 30 Aug 2013, Jürgen Liebmann wrote:
> > Another mystery effect:
> > 
> > I have Ubuntu with the same kernel installed in a virtual machine
> > (virtualbox).
> > 
> > When I plug in the camera in the host the error appears.
> > 
> > Then I plug in the camera in the virtual machine camera works fine.
> > And now I shut down virtual machine.
> > 
> > Now I can use the camera in host until I remove the camera.
> > A new plug in produces the error again.
> 
> This does seem to indicate that the problem is in the camera.
> 
> > Can it be that the time between the both Get-String-Descriptor requests
> > are too small?
>
> You mean the time between the two class-specific requests?  Yes, this
> is possible. (But the commit you found increases that time, so it
> should not have caused the problem to occur.)
> 
> Anyway, if you want to increase the time between those two requests,
> you will have to change the video driver.  Maybe Laurent can help (see
> the analysis below).

Jürgen, could you please try to set the UVC_QUIRK_PROBE_DEF quirk (you can set  
the uvcvideo quirks parameter to 0x100 before plugging your webcam in) and see 
if it helps ?

> > Am 28.08.2013 22:51, schrieb Alan Stern:
> > > On Wed, 28 Aug 2013, Jürgen Liebmann wrote:
> > >> In the attachment the both usbmon traces:
> > >> 
> > >> usbmon-reverted.out  (camera works ok)
> > >> usbmon-74a6af256648  (camera fails)
> > > 
> > > This is very strange indeed.  Here's where the two traces start to get
> > > different results.  In the kernel with the commit reverted:
> > > 
> > > ffff88023073f9c0 742830275 S Co:2:009:0 s 01 0b 0000 0001 0000 0
> > > ffff88023073f9c0 742830331 C Co:2:009:0 0 0
> > > ffff88023073f9c0 742830336 S Ci:2:009:0 s a1 87 0100 0001 001a 26 <
> > > ffff88023073f9c0 742830583 C Ci:2:009:0 -32 0
> > > ffff88023073f9c0 742830592 S Ci:2:009:0 s a1 81 0100 0001 001a 26 <
> > > ffff88023073f9c0 742831081 C Ci:2:009:0 0 26 = 01000101 15160500
> > > 00000000 00000000 00000018 0300fc03 0000 ffff88023073fc00 742831291 S
> > > Ci:2:009:0 s 80 06 0302 0409 00ff 255 < ffff88023073fc00 742831583 C
> > > Ci:2:009:0 0 52 = 34034d00 69006300 72006f00 73006f00 66007400 20004c00
> > > 69006600 65004300
> > > 
> > > This shows a successful Set-Interface request, followed by an
> > > unsuccessful class-specific request and a successful class-specific
> > > request which returns 26 data bytes.  Following that, the computer
> > > reads a 52-byte string descriptor.
> > > 
> > > Now here's the same thing with the commit present:
> > > 
> > > ffff880233820f00 1078447196 S Co:2:008:0 s 01 0b 0000 0001 0000 0
> > > ffff880233820f00 1078447253 C Co:2:008:0 0 0
> > > ffff880233739cc0 1078447266 S Ci:2:008:0 s a1 87 0100 0001 001a 26 <
> > > ffff880233739cc0 1078447523 C Ci:2:008:0 -32 0
> > > ffff880233739cc0 1078447539 S Ci:2:008:0 s a1 81 0100 0001 001a 26 <
> > > ffff880233739cc0 1078447898 C Ci:2:008:0 -32 0
> > > ffff880233739a80 1078448123 S Ci:2:008:0 s 80 06 0302 0409 00ff 255 <
> > > ffff880233739a80 1078448542 C Ci:2:008:0 0 26 = 01000101 15160500
> > > 00000000 00000000 00000018 0300fc03 0000 ffff880233739a80 1078448556 S
> > > Ci:2:008:0 s 80 06 0302 0409 00ff 255 < ffff880233739a80 1078448907 C
> > > Ci:2:008:0 0 52 = 34034d00 69006300 72006f00 73006f00 66007400 20004c00
> > > 69006600 65004300
> > > 
> > > This starts with the same Set-Interface request and the same
> > > unsuccessful class-specific request.  But the second class-specific
> > > request also fails, and the Get-String-Descriptor returns the 26 bytes
> > > of class-specific data!  The Get-String-Descriptor request is repeated,
> > > and this time the device sends the correct 52-byte string descriptor.
> > > After that everything seems to return to normal.
> > > 
> > > I don't understand this at all.  There is no way that commit could
> > > cause the driver to malfunction like this.  The only thing I can think
> > > of is some sort of hardware problem, either in the computer or (less
> > > likely) in the camera.
> > > 
> > > Can you try testing this on a different computer?
> > > 
> > > Alan Stern
-- 
Regards,

Laurent Pinchart

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