USB Backchannel read while printing

[Joel Hess]

I'm developing a driver for a USB printer, and am having a problem with the readbacks that are occuring during printing. The firmware in my printer doesn't know what the request if for, so it fails, and apparently there are a number of retries before it gives up. This is causing a significant slowdown in my print process.

What is the backchannel request expecting for a response so I can resolve the fimware issue? Either that, or is there a way to disable it besides building a different backend that doesn't try the backchannel requests?

Thanks,
Joel Hess