SmartCard: USB Weirdnesses

Georg C. F. Greve greve at
Fri May 6 09:54:46 CEST 2005

 || On Wed, 04 May 2005 21:20:15 +0200
 || "Georg C. F. Greve" <greve at> wrote: 

 gg> The device seems to be reset *after* successfully accessing the
 gg> card.

Actually, when taking a look at the code, I found that in function
do_close_reader in ccid-driver.c the USB reader does indeed get reset
after every single operation.

Since those resets were what made it die, I commented the usb_reset
out and now the SmartCard reader appears to be stable without a USB
Hub even though it has an old bios.

So my feeling is that:

 - unnecessary resets should really be avoided

 - Linux USB code probably has some problem with the way it handles
   the resets that makes devices die since it does not cause problems
   for devices behind a Hub.


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