linux-kernel - Re: Logitech HD Webcam C525 does not work when connected to USB 2 port, works on USB 3

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Date:	Sat, 30 Jun 2012 22:12:07 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Frederik Himpe <fhimpe@...enet.be>
cc:	linux-kernel@...r.kernel.org,
	<linux-uvc-devel@...ts.sourceforge.net>,
	<linux-usb@...r.kernel.org>
Subject: Re: Logitech HD Webcam C525 does not work when connected to USB 2
 port, works on USB 3

On Sat, 30 Jun 2012, Frederik Himpe wrote:

> Hello,
> 
> I've got a Logitech HD Webcam C525 using the uvcvideo module and I use
> Linux 3.5 RC4. When this camera is connected to a USB2 port, it does not
> work most of the time. However it does work fine when connected to a USB
> 3 port. In Windows it works on both ports.

...

> Complete dmesg and lsusb -v output about a failed attempt (on USB 2
> port) and a succeeded attempt (on USB 3) can be found on
> http://artipc10.vub.ac.be/~frederik/webcam/

A usbmon trace would be more helpful.  Or perhaps a pair of traces, one 
for the USB-2 port and one for the USB-3 port.  See the instructions in 
Documentation/usb/usbmon.txt.

Those disconnections in your dmesg logs are not normal.  They could be 
caused by a hardware incompatibility or by a software problem -- 
although if it were software then I would expect the same thing to 
happen with the USB-3 port.

Alan Stern

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