On Mon, 2017-09-18 at 17:49 -0400, Gene Heskett wrote: > On Monday 18 September 2017 11:39:26 Tixy wrote: > > > On Mon, 2017-09-18 at 11:13 -0400, Gene Heskett wrote: > > [...] > > > > > My instant problem, a disappearing usb camera, could also be solved > > > I think, by power cycling the usb port its plugged into, as it will > > > re-appear after a powerdown reboot, but I do not know how to do that > > > short of a powerdown reset. If there is such an ability the user, > > > or a sudo can do, that would also be helpfull. > > > > I don't know if this is useful, but the method I found for resetting a > > USB device was to unbind then rebind it with something like: > > > > echo '3-1.4' >/sys/bus/usb/drivers/usb/unbind > > echo '3-1.4' >/sys/bus/usb/drivers/usb/bind > > > > Where '3-1.4' is the endpoint name for the device found by looking in > > the kernel log. E.g. for this example I ran the 'dmesg' command and > > looked for my web camera and found these entries: > > > > usb 3-1.4: new high-speed USB device number 3 using ehci-pci > > usb 3-1.4: New USB device found, idVendor=2232, idProduct=1018 > > usb 3-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0 > > usb 3-1.4: Product: WebCam SC-13HDL11431N > > > > I don't know if this will help with your particular problem. > > Wheezy apparently isn't organized in quite that manner. So the best I > could do, even as root, was elicit no permissions messages.
Strange, I'm using Jessie, but looks like unbinding has been supported in the kernel for over 10 years [1] so would expect a Wheezy kernel to support it, perhaps the path is different. Does a file at that path exist? For me I get #ls -l /sys/bus/usb/drivers/usb/unbind --w------- 1 root root 4096 Sep 19 06:28 /sys/bus/usb/drivers/usb/unbind Actually, looking at that old article [1] the path is different (/sys/bus/usb/drivers/ub/) so perhaps you might try that, or any other likely path you may have under /sys/bus/usb/drivers/ BTW, I'm sure you realised this, but to make it explicit, the magic string '3-1.4' in my example is specific to my machine and yours will be different depending on the USB hub/device topography. I have no experience with webcam problems so can't help with that specificly. (I use this USB driver unbind/bind trick to get an FTDI development module to toggle it's power enable output) [1] https://lwn.net/Articles/143397/ -- Tixy