Comment 2 for bug 543177
Revision history for this message
| Kevin Goodsell (kevin-goodsell) wrote Re: hybrid usb backend doesn't work with usblp | #2 |
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73416ba
(Get the code!)
I've found some additional details about this problem. First, if I stop the CUPS service before I turn on the printer the probe works fine, and locates the printer as a usblp device. I can then start CUPS and print without issue (I assume... I'm not actually wasting paper testing this, since the failure to discover the printer is the primary issue).
This, and some additional testing, suggest that the problem is related to the timing of the probe. The printers in this line lack the internal memory to store their firmware, and instead load the firmware when they are first turned on or connected. It's obvious to the user when this is happening because the printer noisily "runs" while the firmware loads (the paper rollers turn, I guess). This takes a good 5 or 6 seconds.
I'm hypothesizing that probing the printer while the firmware is loading causes the problem. Maybe it even corrupts the firmware.
Further investigation pending.