Adventures in not actually frying my USB bus

Well, that was exciting. I had an unplanned adventure in technical troubleshooting today.

The symptom: USB isn’t working properly. Low-speed 1.1 devices work, but USB 2.0 appears busted. Rebooting doesn’t fix the problem. Trying other kernels doesn’t fix the problem. The problem also exists in Windows. All googling indicates possible hardware failure. Shit.

I really didn’t want to call tech support, so I actually ran the Dell Diagnostic help tree that comes with their installation of windows. Some of the questions are obvious, like, are the ports physically damaged, but as you drill down it makes a very helpful suggestion: Try running the diagnostics program that came with your computer!

In my case, Dell has a program that will burn a bootable CD. That CD will test the entire system, including the USB subsystem. Interestingly, the diagnostic came back clean. How can USB be busted if the tests are ok?

Ultimately, I have no idea, because when I rebooted into Windows the problem was gone. Booting back into linux, the problem was fixed there too. And here I thought I would have to replace the motherboard because of a burnt-out usb system.

The first moral of the story: It is possible for linux to fuck up USB so bad, a reboot and power-cycle won’t fix it.

The second moral of the story: It’s really nice to have windows around when you want to see if a problem is linux-specific, or hardware-specific. (The same goes the other way. If you have windows installed, it’s nice to have a linux installation, or at least a boot disc, so you can try stuff out.)

The third moral of the story: Even if you think you are technically able, don’t jump to the conclusion that a problem is fucked hardware. Go through the motions of troubleshooting the problem, and who knows, it might actually be fixable without mailing your part in for service. I was this close to calling Dell, and there would have been no need.

Edit:
Hrm. Well, the usb died again. This time the dell diagnostic didn’t bring it back. Time to call tech support

Edit 2:
Double hrm. Spent an hour on the phone and screen sharing with Dell tech support, who proved completely immune to my evidence that this was a hardware issue, not a software issue. They installed some driver and the problem went away, but I think it’s just like last time — it randomly fixed itself and the problem still remains. The best part was when the tech support person suddenly decided to become a sales rep and asked me why I hadn’t bought dell’s extra Accidental Protection Plan or some shitty tuneup software. Way to put progressbar time to good use, assholes.