cupsBackChannelWrite purpose?

[Michael Sweet]

albert kennis wrote:
> I would like to know who the intended client of the cupsBackChannel
> is.  I can see from the read_thread function in usb-darwin.c that
> data is being blindly read in from the printer and written out
> accross this channel.  What is not obvious is who and how this data
> is being consumed.

Printer drivers and port monitors can read this data back via the
cupsBackChannelRead() function.  Typically this is used to communicate
status and configuration information from the printer to the driver.

> Unfortunately our printer devices are misbehaving when usb bulk read
> requests are interleaved with usb bulk write requests.
> 
> Is there any way to wholly disable this behaviour?

Not at present.  The UNIX character device version disables the
back-channel for Canon and Minolta devices, but there is no
equivalent in usb-darwin.c.

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Publishing Software        http://www.easysw.com