Accessing a USB device

[Janina Sajka]

Do you have an uhci-hcd module loaded? I have the following statement in my
(Fedora) /etc/modprobe.conf:

alias usb-controller uhci-hcd

I found the following web site helpful, by the way:

http://www.linux-usb.org/USB-guide/book1.html

Chuck Hallenbeck writes:
> 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
> 
> 
> -- 
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> 
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-- 

Chair, Accessibility Workgroup		Free Standards Group (FSG)
janina at freestandards.org		http://a11y.org

Janina Sajka				Phone: +1.202.494.7040
Partner, Capital Accessibility LLC	http://www.CapitalAccessibility.Com

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