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Message-ID: <20120711061114.GA1596@fancy-poultry.org>
Date: Wed, 11 Jul 2012 08:11:14 +0200
From: Heinz Diehl <htd@...cy-poultry.org>
To: linux-kernel@...r.kernel.org
Cc: Frederik Himpe <fhimpe@...enet.be>,
USB list <linux-usb@...r.kernel.org>,
Alan Stern <stern@...land.harvard.edu>
Subject: Re: Logitech HD Webcam C525 does not work when connected to USB 2
port, works on USB 3
Hi,
I have exactly the same webcam, lsusb says "Bus 002 Device 004: ID
046d:0826 Logitech, Inc."...
On 06.07.2012, Alan Stern wrote:
> On Thu, 5 Jul 2012, Frederik Himpe wrote:
> > I tried setting to on again, and then this appears in the logs:
> > Jul 5 21:21:59 piranha kernel: [ 9788.223118] usb 1-1.2: USB disconnect, device number 6
> > Jul 5 21:22:00 piranha kernel: [ 9788.330415] usb 1-1.2: new full-speed USB device number 7 using ehci_hcd
> > Jul 5 21:22:00 piranha kernel: [ 9788.402207] usb 1-1.2: device descriptor read/64, error -32
> > Jul 5 21:22:00 piranha kernel: [ 9788.577706] usb 1-1.2: device descriptor read/64, error -32
> > Jul 5 21:22:00 piranha kernel: [ 9788.753203] usb 1-1.2: new full-speed USB device number 8 using ehci_hcd
> > Jul 5 21:22:00 piranha kernel: [ 9788.824996] usb 1-1.2: device descriptor read/64, error -32
> > Jul 5 21:22:00 piranha kernel: [ 9789.000493] usb 1-1.2: device descriptor read/64, error -32
[....]
...and I do not have these messages at all, with or without
autosuspend enabled...
> In the long run, it may be necessary to add a quirk entry to always
> use a reset-resume with this device. You can find similar entries in
> drivers/usb/core/quirks.c for other Logitech webcams, which makes it
> seem very likely that one is needed for yours. If you want you
> can try adding the appropriate entry and submit it as a patch.
...and it runs fine with or without the quirk, which I added for
testing purposes.
> None of this explains why there isn't any problem when the webcam is
> plugged into a USB-3 port, unfortunately.
All this is purely on USB-2, my machine doesn't have any USB-3 port,
with vanilla 3.4.4 kernel. If nobody did, should I submit a patch
containing the quirk anyway?
If I can help testing, feel free to contact me.
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