[cups.general] Unable to print to USB

[Johannes Meixner]

Hello Tim,

On Feb 24 10:59 Tim Waugh wrote (shortened):
> On Wed, 2010-02-24 at 10:48 +0100, Johannes Meixner wrote:
>
>> Therefore - as far as I understand it - even if the HPLIP filter
>> would use the CUPS back-channel for printer status info, it would
>> not work to use the generic CUPS "usb" backend for printing
>> while the hpaio SANE driver can still be used for scanning.
>
> You can use the usb backend to print to HP multifunction printers.

Perhaps with the new libusb based CUPS "usb" backend in CUPS 1.4
but not with the usblp based CUPS "usb" backend up to CUPS 1.3
because there is a libusb/usbfs versus usblp conflict in the kernel
so that one cannot use both USB drivers for the same USB device
at the same time.

> You cannot scan while printing even if you are using the hp backend.

Of course scanning and printing are mutual exclusive
but I never tested if mutual exclusion works well
when for printing the libusb based CUPS "usb" backend
is used and - while printing is active - a scanning attempt
is done and vice versa.

I still think that using a single piece of software which does
the "multiplexing" (more precisely the mutual exclusion)
is the more fail safe way to operate HP all-in-one devices.


Kind Regards
Johannes Meixner
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