I think the NULL pointer dereference is red herring here, the disconnection is
where problem occurs:
júl 22 21:12:50 lenovo kernel: usb 3-2: USB disconnect, device number 2
So we need to know why the webcam disconnected right before it starts streaming.
Please add "xhci-pci.dyndbg=+p xhci-hcd.dyndbg=+p usbcore.dyndbg=+p" to the
kernel parameter, reproduce the bug, then attach dmesg.
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Lenovo e73 USB webcam problems
Status in linux package in Ubuntu:
I'm experiencing problems with USB webcam on Lenovo e73 with Ubuntu
16.04.2 Xenial 32bit.
Originally with 4.4 connecting the camera often resulted in complete
hang of the system (apparently not even SysRq worked, though I did not
test that personally since it is a system I'm administering remotely
for a family member). There was always a null pointer dereference just
before the hang, so I suspect that is the culprit (see the attached
After some updates the system no longer hangs. I suspect this was fixed by
going from linux 4.4 to 4.8. However, the webcam still often doesn't work and
most application just return error. This is usually fixed after several tries,
but sometimes it is necessary to reboot computer. Updating BIOS didn't help.
The kernel logs still contain the same null pointer dereference with exactly
the same stack trace for both 4.8 and 4.10.
USER PID ACCESS COMMAND
/dev/snd/controlC2: user 1852 F.... pulseaudio
/dev/snd/controlC0: user 1852 F.... pulseaudio
/dev/snd/controlC1: user 1852 F.... pulseaudio
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2017-05-05 (85 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release i386 (20151021)
tun0 no wireless extensions.
enp2s0 no wireless extensions.
lo no wireless extensions.
MachineType: LENOVO 10DR002SMC
Package: linux (not installed)
PATH=(custom, no user)
ProcFB: 0 inteldrmfb
root=UUID=07f94680-ac2c-498b-86e4-72ff6e4bd18f ro quiet splash
ProcVersionSignature: Ubuntu 4.8.0-58.63~16.04.1-generic 4.8.17
Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not
accessible: Permission denied
No PulseAudio daemon running, or not running as session daemon.
Uname: Linux 4.8.0-58-generic i686
UpgradeStatus: Upgraded to xenial on 2017-05-05 (85 days ago)
dmi.board.version: SDK0G00599 WIN
dmi.product.version: ThinkCentre E73
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