I just made another test : I stopped the cups service, loaded usblp with modprobe, and ran :
cat lines.ps | gs -q -sDEVICE=ppmraw -r600 -sPAPERSIZE=letter -dNOPAUSE -sOutputFile=- - | pnm2ppa --eco -v 720 -i - -o - > /dev/usb/lp0
so : lines.ps contains 56 lines to be printed, which fails with cups+libusb : here : SUCCESS !
I am not sure that this helps for my diagnostic - it just tells that cups + usblp is flawed with my devices ...
I just made another test : I stopped the cups service, loaded usblp with modprobe, and ran :
cat lines.ps | gs -q -sDEVICE=ppmraw -r600 -sPAPERSIZE=letter -dNOPAUSE -sOutputFile=- - | pnm2ppa --eco -v 720 -i - -o - > /dev/usb/lp0
so : lines.ps contains 56 lines to be printed, which fails with cups+libusb : here : SUCCESS !
I am not sure that this helps for my diagnostic - it just tells that cups + usblp is flawed with my devices ...