My Brother HL-1440 would print one document before CUPS would stop
printing with the error "Printer not connected; will retry in 30
seconds...". I traced this down to the CUPS usb backend getting an EIO
out of usblp on the IOCNR_GET_DEVICE_ID IOCTL. Adding the
USBLP_QUIRK_BIDIR fixes the problem but is it the right solution?

output from strace /usr/lib/cups/backend/usb after printing a document
(Note: SNDCTL_DSP_SYNC == IOCNR_GET_DEVICE_ID):

before patch

open("/dev/usb/lp0", O_RDWR|O_EXCL)     = 3
ioctl(3, SNDCTL_DSP_SYNC, 0x7fff2478cef0) = -1 EIO (Input/output error)

after patch

open("/dev/usb/lp0", O_RDWR|O_EXCL)     = 3
ioctl(3, SNDCTL_DSP_SYNC, 0x7fffb8d474c0) = 0

Possibly related bug: https://bugs.launchpad.net/ubuntu/+source/cupsys/+bug/35638Signed-off-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>