# Thinkpad w510 webcam freeze, why oh why?

## pking

I have a Thinkpad w510 with an integrated webcam [Lenovo Integrated Webcam R5U877].  Support for V4L is present in the kernel (gentoo-sources-3.0.0) as modules, and all modules seem to be loaded properly upon boot, including the 32bit compatibility library. And when I run applications that make use of the webcam, such as guvcvideo or skype, the webcam does in fact turn on and show a picture. Briefly. After a short period of time, about 10-15 seconds, the picture freezes as does the entire computer, and a hard reboot is required to get things working again. No useful information is found in the logfiles at all. I've googled around but nobody else so much as hints at a problem with video on this laptop. Nor can I find any bugs filed against (say) uvcvideo that seem responsible for the behaviour. Given that the problem crops up in two different programs, I'm inclined to suspect the kernel driver, or some deep misconfiguration on my part somewhere. I can't think of where to look next for information, though, so I thought I'd give all the experts here a chance to show what they know   :Sad: 

Let's see. The webcam is recognized by lsusb, and the requisite kernel modules seem to be loaded -- at least, the same modules as are loaded on my x120e, on which video works flawlessly. The kernel version is 3.0.0. I can't really say whether the webcam has ever worked properly before because I don't usually use or need it, though I do now (of course). I can post dmesg, kconfig, etc. as needed to help debug the problem, but I don't know which of them if any might be of some use. Take this as a cry in the wilderness...

----------

## Hypnos

As for kernel configuration, all you should need is this.

If you suspect a kernel bug, have you tried a different kernel version?  Does the webcam work under a different OS, like Windows?

EDIT: It seems that a few people are having similar difficulties (link1, link2) around the same time kernel 3.0 came out.  If your webcam ever worked in Linux, I would try a kernel older than 3.0 to see if there was a regression in the uvc driver.

----------

## pking

Drat! Thanks for the info, although I was afraid of that...

My kernel version is actually gentoo-sources-3.3.0, but that doesn't matter. I have the suggested options enabled in the kernel. Looks like a problem in the uvcvideo driver that shows up under some architectures (intel 64-bit) with some webcams (such as mine). The next thing to check is whether the same problem shows up in earlier kernel versions, or under other OSs. I guess that's what LiveCDs are for!

----------

## pking

It turns out to be hard to find a liveCD or liveDVD that has Skype installed. I eventually found one called ExLight, which is a Swedish repackaging of Ubuntu using Enlightenment as the window manager, running i686. I used unetbootin to install it on a USB flash drive. Rebooted my Thinkpad w510, and lo and behold, under kernel 3.0.6 (I believe), Skype works. So it has something to do with the kernel configuration under gentoo on my multilib system. I tried preloading the 32bit-compatibility library before and that didn't work, but perhaps I should try it again. So curiouser and curiouser... the hardware is fine, and at least one 32bit version of Linux (with an earlier kernel) is fine. So where's the problem?

----------

## Hypnos

1) To check the function of the webcam, you don't need skype -- any webcam application would do, no?  From the commandline you could do "mplayer tv://" or in GNOME you can use Cheese.

2) Why not try kernel 3.0.x and see if it works?  Perhaps the uvcvideo bug cropped up between 3.0.x and 3.3.x .

----------

