USB webcam weirdness

[Net Llama!]

On Tue, 30 Nov 2004, Roger Oberholtzer wrote:
> On Tue, 2004-11-30 at 07:25 -0500, Net Llama! wrote:
> > I've got a Philips 690 USB webcam, which was working flawlessly until I
> > started using it on an old laptop running FC3.
> >
> > Now it runs ok for several hours (where several is anywhere from 12-15)
> > and then it suddenly stops capturing images.  The weird thing is that its
> > not generating any errors, its just that the image which is getting
> > captured is blank.  Here's what i'm referring to:
> > http://netllama.linux-sxs.org/llamava/home.jpg
> >
> > What you should be seeing is the view from outside my living room window.
> >
> > I've checked messages log and there are no errors.  Everything that is
> > logged is as if all is normal.  The only way i've found to fix this right
> > now is to manually unplug and replug the camera into the USB port.  Then
> > it works fine again for several hours, and the cycle begins again.
> >
> > Since there are no errors anywhere, i'm at a bit of a loss as to what is
> > going on.  Anyone have any suggestions on how to troubleshoot this
> > further?
>
> You unplug the camera and that is all? You do not restart any software?
> Not even the USB drivers?

Well the kernel tools handle unloading and loading drivers transparently,
so that does happen as well.  I did try rmmod'ing and modprobing the pwc
module for the camera, but that didn't help.  I guess i could try manually
unloading all the assorted modules and see if that has the same function
as un/re-plugging the camera.

Is there a way to reset the USB bus?

> After 12-15 hours of images, might it just be getting dark outside :)

Well sure, but the camera ran fine overnight last night.  It actually does
a pretty decent job of handling lighting changes.  I checked it this
morning at around 6AM, and it was still working, but at 7AM i get the
image that I noted above.

> Don't laugh. I ran an all night test of a firewire capture system and
> initially got concerned when the images got both smaller and darker.
> Then it dawned on me. Literally.

Well yea, but i'm seeing the reverse of that behavior.  THe camera seems
to die at dawn  *shrug*

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lonni J Friedman                                netllama at linux-sxs.org
Linux Step-by-step & TyGeMo                  http://netllama.ipfox.com