Hi Laurent,
Thank you very much for your quick reply and sorry for getting back to
you only today, your message got moved to a different folder by a
filter rule I did not remember of.
On Wed, 23 Oct 2019 17:20:16 +0300, Laurent Pinchart wrote:
> On Wed, Oct 23, 2019 at 03:18:59PM +0200, Jean Delvare wrote:
> > When my Logitech C270 webcam is plugged in, my kernel log gets filled
> > with this message:
> >
> > usb 3-4.1: reset high-speed USB device number 4 using xhci_hcd
> >
> > every 5 seconds. I have the same problem on 3 different Intel-based
> > computers (different generations), using 2 different webcams, same
> > brand "same model".
> >
> > Is Logitech doing crappy hardware these days, or are we doing something
> > wrong? Is there any way to know the reason that triggers the reset?
>
> Is this before or after the uvcvideo driver gets involved ? One easy way
> to check is to move the uvcvideo.ko module out of the way so that it
> doesn't get loaded automatically (or just blacklist it in
> /etc/modprobe.d/) and then plug the camera.
I did as you suggested and it turns out that the "reset high-speed USB
device" messages are not printed originally, they start being printed
right after the uvcvideo kernel driver gets loaded. So that would be a
problem with the uvcvideo driver?
When unloading the uvcvideo driver, there's one more "reset high-speed
USB device" message and then no more.
For what it's worth, 2 things worth noting in the kernel log when the
device is being detected:
usb 3-12: set resolution quirk: cval->res = 384
(...)
uvcvideo: Found UVC 1.00 device <unnamed> (046d:0825)
"<unnamed>" seems weird. On the other hand lsusb properly lists it as:
Bus 003 Device 004: ID 046d:0825 Logitech, Inc. Webcam C270
I an older C270 webcam (3 year old, different package) connected to
another machine, USB device ID is the same, I compared the verbose
output of lsusb and one difference stands out:
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
VideoStreaming Interface Descriptor:
(...)
- bmaControls( 0) 27
- bmaControls( 1) 27
- bmaControls( 2) 27
+ bmaControls( 0) 0
+ bmaControls( 1) 4
+ bmaControls( 2) 4
(- is the new webcam, + is the old one)
I don't know if this tells anything useful though.
Thanks,
--
Jean Delvare
SUSE L3 Support
