* [gentoo-user] U.V.C. Webcam Disconnects shortly after Registration
@ 2020-12-25 3:56 Ashley Dixon
2020-12-25 11:34 ` Michael
0 siblings, 1 reply; 2+ messages in thread
From: Ashley Dixon @ 2020-12-25 3:56 UTC (permalink / raw
To: Gentoo Users
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How's it going dudes?
I bought a Logitech C270 webcam from Argos about a year ago, which, according to
the LKDDb [1] and U.V.C. driver website [2], should work well on Linux. Despite
working flawlessly until recently, some strange behaviour has appeared.
When I connect the webcam, `dmesg` registers it as would be expected (timestamps
omitted):
usb 3-7: new high-speed USB device number 14 using xhci_hcd
usb 3-7: New USB device found, idVendor=046d, idProduct=0825, bcdDevice= 0.12
usb 3-7: New USB device strings: Mfr=0, Product=0, SerialNumber=2
usb 3-7: SerialNumber: 9EEFE4E0
uvcvideo: Found UVC 1.00 device <unnamed> (046d:0825)
input: UVC Camera (046d:0825) as /devices/pci0000:00/0000:00:14.0/usb3/3-7/3-7:1.0/input/input27
usb 3-7: set resolution quirk: cval->res = 384
However, about two seconds later, me having done nothing, the kernel ring buffer
suggests it has been physically unplugs, and thus deregisters the device...
USB disconnect, device number 14
I have tested this on another very similar machine, and this problem is not to
be seen, and everything works perfectly; thus ruling out a hardware issue with
the camera. Furthermore, no other devices---even other U.V.C. webcams---do not
present with the same symptoms on my machine, in the same U.S.B. port; thus
ruling out any issue with the physical port or motherboard controller.
I have no idea how to triage this further. I feel like my head has been nailed
to a coffee table by Dinsdale Piranha. Any tips? My kernel is 5.9.13-zen1,
although this trouble presents identically on a vanilla kernel.
Cheers.
Hope everyone is remaining well.
[1] https://linux-hardware.org/index.php?id=usb:046d-0825
[2] https://www.ideasonboard.org/uvc/#devices
--
Ashley Dixon
suugaku.co.uk
2A9A 4117
DA96 D18A
8A7B B0D2
A30E BF25
F290 A8AA
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [gentoo-user] U.V.C. Webcam Disconnects shortly after Registration
2020-12-25 3:56 [gentoo-user] U.V.C. Webcam Disconnects shortly after Registration Ashley Dixon
@ 2020-12-25 11:34 ` Michael
0 siblings, 0 replies; 2+ messages in thread
From: Michael @ 2020-12-25 11:34 UTC (permalink / raw
To: Gentoo Users
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On Friday, 25 December 2020 03:56:58 GMT Ashley Dixon wrote:
> How's it going dudes?
>
> I bought a Logitech C270 webcam from Argos about a year ago, which,
> according to the LKDDb [1] and U.V.C. driver website [2], should work well
> on Linux. Despite working flawlessly until recently, some strange
> behaviour has appeared.
Have you changed anything recently on this PC, coincidental with this problem
arriving? Anything related to kernel/drivers, webcam related apps and audio?
Besides dmesg, do you get any other errors in syslog?
Have you disconnected all other USB devices on other ports hanging off the
same MoBo USB hub controller?
> When I connect the webcam, `dmesg` registers it as would be expected
> (timestamps omitted):
>
> usb 3-7: new high-speed USB device number 14 using xhci_hcd
> usb 3-7: New USB device found, idVendor=046d, idProduct=0825,
> bcdDevice= 0.12 usb 3-7: New USB device strings: Mfr=0, Product=0,
> SerialNumber=2 usb 3-7: SerialNumber: 9EEFE4E0
> uvcvideo: Found UVC 1.00 device <unnamed> (046d:0825)
> input: UVC Camera (046d:0825) as
> /devices/pci0000:00/0000:00:14.0/usb3/3-7/3-7:1.0/input/input27 usb 3-7:
> set resolution quirk: cval->res = 384
>
> However, about two seconds later, me having done nothing, the kernel ring
> buffer suggests it has been physically unplugs, and thus deregisters the
> device...
>
> USB disconnect, device number 14
I don't have the same camera, but it could be something related to power.
When the device is detected and initialised by udev + kernel driver, it starts
drawing more current to deal with features like autofocus/exposure. Once it
settles the current consumption reduces.
> I have tested this on another very similar machine, and this problem is not
> to be seen, and everything works perfectly; thus ruling out a hardware
> issue with the camera. Furthermore, no other devices---even other U.V.C.
> webcams---do not present with the same symptoms on my machine, in the same
> U.S.B. port; thus ruling out any issue with the physical port or
> motherboard controller.
Not necessarily.
Stating the obvious, other machines are not the *same* machine. Differences
in mV/μA between MoBos could cause a marginal case to manifest itself.
Other UVC webcams, are not the same webcam in terms of sensitivity and
electrical consumption.
> I have no idea how to triage this further. I feel like my head has been
> nailed to a coffee table by Dinsdale Piranha. Any tips? My kernel is
> 5.9.13-zen1, although this trouble presents identically on a vanilla
> kernel.
Do you have an external USB hub, with its own separate power supply, to see if
connecting the camera to it overcomes with this problem?
Check if the driver has any power saving features with 'modinfo' and if
switchable, disable them and try again.
Camera sensors and chips can degrade over time and change their performance
with differences in temperature. I appreciate a year is not long enough, but
I had camera sensors fail in a matter of months - thankfully still under
warranty.
> Cheers.
>
> Hope everyone is remaining well.
>
> [1] https://linux-hardware.org/index.php?id=usb:046d-0825
> [2] https://www.ideasonboard.org/uvc/#devices
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