I am trying for the first time to access a USB device and having a problem doing so. The device is my new UPS from American Power Conversion, which I plan to monitor with a program called apcupsd. The manual describes how to configure my system for USB and how to test the USB interface before running the program, and that is where I am stuck. It appears to me to be an interrupt problem. Here is why I think so. For the past month or two I have noticed a peculiarity that happens within about a minute after booting up the computer. Normally I start logging in various users on difference consoles, and while I am doing that, I get a spontaneous message saying that IRQ 5 is being disabled. The message says something cute like, "Nobody cares!" and then disables IRQ 5. Examining the IRQ assignments, I see that the only device assigned to that IRQ shown in /proc/interrupts is the uhci-hcd driver. That has not been a problem until now, since until now I have not attempted to access a USB device, which requires the uhci-hcd driver. When I plug the cable from my UPS into a USB slot, the device is correctly identified by manufacturer, serial number, etc., but then it says that it fails to register with usbcore. And the test program confirms that the device cannot be accessed. My kernel is 2.6.11.6, and all the relevant drivers are compiled into the kernel. It looks to me like the uhci-hcd driver has been assigned to IRQ 5 but is not responding to that interrupt when it occurs. If someone has seen this kind of thing before, or has any suggestion how to proceed with troubleshooting this one, I would sure appreciate hearing about it. The software I plan to run to monitor the UPS is not involved here as yet, since I have to resolve the USB interface to the UPS before there is a hope in hell of that software working. If it would be of value to share any of the error messages or other data, I would be happy to do so. Any ideas? I have run out. Chuck -- The Moon is Full But you can still get downloads from http://www.mhcable.com/~chuckh
