Oct 21, 2011 by Henry Wong :
Attached file: cups-1.6-r10087-usb-skip-interface-altsetting.patch
Oct 21, 2011 by Henry Wong :
See http://blog.stuffedcow.net/2011/10/samsung-linux-cups-usb-printing/
Some printers (e.g., Samsung ML-2010, Samsung ML-1740) don't tolerate being sent a SET_CONFIGURATION or SET_INTERFACE request after the printer has already been configured. Sending these extra requests are legal under the USB spec, but it causes my printer to often ignore subsequent print jobs after the first one. These problems did not occur using usblp.
The libusb backend sends SET_CONFIGURATION and SET_INTERFACE requests before every print job. Under usblp, these are not (verified by capturing a USB trace).
This patch first makes the libusb backend first query whether sending SET_CONFIGURATION and SET_INTERFACE are necessary before sending them, bringing the behaviour closer to usblp. It also fixes the problems with my Samsung printers.
With this patch, the only remaining difference between usblp and libusb is that a GET_CONFIGURATION request is sent before each print job, whereas usblp assumes without verification that the printer is already using the correct configuration. The GET_CONFIGURATION request was added by this patch because I wasn't comfortable with blindly assuming the currently-selected configuration is correct.
This problem is probably related to STR #3964, and may also fix that issue, without needing to do an intrusive USB reset.
Nov 11, 2011 by Till Kamppeter:
I have applied this patch and the patch of STR #3978 to the package in Ubuntu Oneiric now and asked the people suffering the following Ubuntu bugs for testing:
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/887094
usb printer backend crashes
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/872483
laser printer only prints first job correct
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/883169
Brother MFC-8840D usb printer not detected
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/793244
After suspend/hibernate usb printer backend repeatedly crashes
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/564917
Ubuntu 10.04 does not recognize local printer connected via
USB/parallel adapter cable
For the first three I got answers and they are definitely fixed by the two patches. On the other two I am still waiting for an answer but they are most probably also fixed.
Together with the USB fix on the Linux kernel (STR #3884) it looks like that all known problems of libusb-based USB printing (after deprecation of the "usblp" kernel module) are solved together with these two patches on the libusb-based "usb" CUPS backend. So I highly recommend the inclusion of the two patches in the upstream repository of CUPS, for both CUPS 1.5.x and 1.6.x.
Dec 14, 2011 by Michael Sweet:
This should be applied to CUPS 1.5.
Jan 27, 2012 by Michael Sweet:
Attached file: str3965+3978.patch
Jan 27, 2012 by Michael Sweet:
Fixed in Subversion repository.