I have done further tests, also with some slight modifications on the
USB CUPS backend and found out that the USB->Parallel adapter is rather
instable. Forced uni-directional mode improves on its stability, also
blacklisting the usblp kernel module, but one can prove that the problem
is not a bug of the CUPS backend. It is probably somewhere in the
kernel. Following observations lead to this:
1. With the usblp module not blacklisted and loaded I cannot get the
device ID through the kernel module.
sudo usb_printerid /dev/usb/lp0
gives an I/O error for me.
till@till:~/ubuntu/cups/bzr/precise/cups-1.5.3$ sudo usb_printerid /dev/usb/lp3
[sudo] password for till:
Error: Input/output error: GET_DEVICE_ID on '/dev/usb/lp3'
till@till:~/ubuntu/cups/bzr/precise/cups-1.5.3$
2. "lsusb" sometimes does not show the adapter, "sudo lsusb -vvv"
sometimes hangs infinitely.
Adding kernel and libusb tasks.
** Also affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Also affects: libusbx (Ubuntu)
Importance: Undecided
Status: New
** Changed in: libusbx (Ubuntu Precise)
Status: New => Invalid
** Also affects: libusb-1.0 (Ubuntu)
Importance: Undecided
Status: New
** Changed in: libusb-1.0 (Ubuntu)
Status: New => Invalid
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https://bugs.launchpad.net/bugs/987485
Title:
Can only print once with USB to parallel adapter and HP 4L
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