SmartCard: USB Weirdnesses

Georg C. F. Greve greve at
Wed May 4 12:54:18 CEST 2005

Hi all,

since we have shipped our Fellowship cards now, I am switching to
using my Fellowship card in production... and have eliminated the
first problems in terms of integration with Gnus already.

I have been testing things with the SCM SCR-335 & SPR-532 readers and
always had the result that they crashed *very* frequently. Sometimes
consistently after a single operation.

Talking with Werner, he had made good experience with upgrading the
Firmware, but that could not be the whole explanation, imho, as they
seem to work stable under Windows regardless of the firmware.

I am not a USB expert and this may in fact be a Linux kernel problem,
but I would still like to share my observations with you:

 * USB reader connected directly to computer: TROUBLE

 * USB reader AND USB memory stick connected to computer: TROUBLE

 * USB reader connected to external USB Hub: WORKS LIKE CHARM

 * USB reader AND USB memory stick connected to USB Hub: TROUBLE

This is reproduceable.

So it appears there is some oddness going on -- potentially in the
Linux USB Code -- that screws things up for the readers.

How are the experience values of the others?

Can we help tracking that problem down so the USB maintainers know
where to look and how to fix it?


Georg C. F. Greve                                 <greve at>
Free Software Foundation Europe	                 (
Join the Fellowship and protect your freedom!     (
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