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