I have received a brand new USB card reader.

At first sight, everything was working well “out of the box”, but when I have checked the log files, I could see the following lines repeated very frequently:

Jun  1 08:22:08 athyr kernel: [ 1412.134045] usb 6-2: reset high speed USB device using ehci_hcd and address 3

I repeat everything seems to work OK, but I can’t stand this kind of messages, especially when it deals with storage (by experience, everything works well during the tests, you simply ignore error messages, and you loose your data the first time you really use your hardware!).


After some googling, I have found this issue is hardware related. A lot of people seem to get hit by this. Some have even reverted to USB 1 (UHCI)!

Further googling pointed out this article.

I have tried to disable USB auto-suspend, and changing the idle-delay time (default is 2 seconds). But it doesn’t help.

Just for reference, this can be done like this:
echo -1 > /sys/module/usbcore/parameters/autosuspend

Note the following part of the documentation:
The idle-delay values for already existing devices will not be affected

To make the change permanent, you need to append usbcore.autosuspend=-1 to the boot parameters (USB support is compiled into Debian kernels).
More information on: http://www.mjmwired.net/kernel/Documentation/usb/power-management.txt

I can also see the following message at boot time:

unable to enumerate USB device on port 4

According to this recent discussion, it seems it is harmless.

I have however noticed that unplugging the card reader and re-plugging it after the system has booted make these log entries disappear. Does someone have an idea?

Note that I use the latest Debian 2.6.25 kernel:

$ uname -a
Linux athyr 2.6.25-2-amd64 #1 SMP Tue May 27 12:45:24 UTC 2008 x86_64 GNU/Linux