I don't know if any kernel hackers browse this forum, but if they do, here is a small heads-up about a problem I found.
Let me start by saying that I am a great admirer of the kernel help system. It's undoubtedly the best and most informative help documentation that I have ever come across. But there is a conflict developing between kernel help and cups about this module.
The help says:
Quote:
config USB_PRINTER
Say Y here if you want to connect a USB printer to your computer's
USB port. To compile this driver as a module, choose M here: the
module will be called usblp.
|
This is quite unequivocal: if you want to use a usb printer, you need the usblp driver in some form.
But cups has not used this driver for some time. It now uses libusb. In fact most installations of cups come with a blacklist file for the usblp module because it causes interference.
Intermittently there are bugs in cups that stop the blacklisting of usblp from working. I recently upgraded cups to 2.2.4 in Crux and my usb printer suddenly went dead. Jobs were put into the queue but couldn't get to the printer. Running /usr/lib/cups/backend/usb by hand showed the message "DEBUG: Failed to detach "usblp" from 03f0:7511" (the usb identifier shown is that of my printer, an HP Photosmart). I googled a bit and found that the same problem had occurred a couple of years ago in an earlier version of cups. Clearly it had since been corrected and is now recurring.
I rebuilt the kernel without usblp and cups now works normally again. It looks as if the kernel help for this module needs a rewrite.
