Hi Tom, Henning Meier-Geinitz <henn...@meier-geinitz.de> writes:
> Hi, > > On Wed, Jun 09, 2004 at 04:48:51PM +0100, Tom Schutzer-Weissmann wrote: >> I had problems using the Epkowa libraries (libsane-epkowa) and the >> iscan frontend with my usb scanner in kernel 2.6. > >> The scanner was closed after each operation. Once closed, nothing >> could be read from it, and I got lots of BULK TIMEOUTs, although >> there were no errors when the device was reopened. >> >> By modifying the code so that usb_reset() was always called before >> usb_release_interface() and usb_close(), I solved the problem. > > Doesn't usb_reset() cause a renumeration and therefore the device gets > a new device file? I guess this isn't the default for closing USB > devices. Maybe the usb_reset just hides a bug in the SANE backend, > libusb or the kernel. Henning is right about the re-enumeration. As far as I understand the docs, that means that after calling usb_reset(), you may no longer use the handle you have. Problem is, it *is* used twice after that call. If the documentation is serious about this re-enumeration, than your "fix" is incorrect and has the potential to break support for *all* SANE supported USB devices. That it works for you is mere coincidence. FYI: http://libusb.sourceforge.net/doc/function.usbreset.html That leads us to a bug in the epson/epkowa backends, quite possibly caused by undocumented behaviour of this particular scanner. :-( -- Olaf Meeuwissen EPSON KOWA Corporation, PF1 FSF Associate Member #1962 sign up at http://member.fsf.org/ GnuPG key: 6BE37D90/AB6B 0D1F 99E7 1BF5 EB97 976A 16C7 F27D 6BE3 7D90 Penguin's lib! -- I hack, therefore I am -- LPIC-2
