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Re: Problems writing to USB devices

To: Giuseppe Sacco <>
Subject: Re: Problems writing to USB devices
From: "J. Scott Kasten" <>
Date: Wed, 17 Oct 2007 09:14:08 -0400 (EDT)
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On Wed, 17 Oct 2007, Giuseppe Sacco wrote:

Hi all, I am still testing new kernels on the ip32 platform (and learning kernel structure :-)). Currently I found problems in writing to USB block devices. I may read from a pendrive without problem, but when I try to write the process stop. This is the last part of a transcript of strace output for "pvcreate /dev/sdc" command:

A few questions...

* Which USB card, or more precisely, which chipset is on the USB card you picked?

I've had great luck with NEC and ALI chips thus far.

* Which driver was loaded for the USB controller, OHCI, UHCI, EHCI?

If you have a USB 2.0 controller, the system will probably try to load both EHCI and UHCI. I did run into problems there, for one, the system crashed when I pulled the thumb drive out. It sometimes behaved strangely when it was in. I eventually figured out that removing UHCI and running EHCI only was the solution for me. The UHCI module seemed to be probing the hardware incorrectly. It was reporting 6 ports on the bridge when there were only 2. The EHCI module was reporting the correct number as I recall. Once it was EHCI only, I've never had a problem since.

That was originally under 2.6.17 from gentoo. I've since been using the debian patched 2.6.18. I'm afraid I haven't yet reached sufficient motivation to move into the 20's like the rest of you. I tend to like my box working... :) Just's on the todo list.


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