Skip site navigation (1)Skip section navigation (2)
Date:      Sat, 01 Jul 2006 18:33:25 +0200
From:      Jan-Espen Pettersen <sigsegv@radiotube.org>
To:        Rainer Heesen ------- <rainer.heesen@gmx.de>
Cc:        asa@agava.com, freebsd-questions@freebsd.org
Subject:   Re: CUPS, USB printers & "Permission Denied"
Message-ID:  <44A6A3D5.9020607@radiotube.org>
In-Reply-To: <200606301737.32015.rainer.heesen@gmx.de>
References:  <200606301737.32015.rainer.heesen@gmx.de>

next in thread | previous in thread | raw e-mail | index | archive | help
This is an OpenPGP/MIME signed message (RFC 2440 and 3156)
--------------enigBA648173365A5A7F6A220B8A
Content-Type: multipart/mixed; boundary="------------030401040401020208000605"

This is a multi-part message in MIME format.
--------------030401040401020208000605
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

Rainer Heesen ------- wrote:
> I have a Minolta PagePro 1350 printer. When I use the workaround I get =
the=20
> error 'raw printers cannot use file: devices!'
>
> Is there another workaround?
>
> rainer@desktop ~$ lpstat -d -p -t
> system default destination: Minolta
> printer Minolta disabled since Fri Jun 30 17:14:11 2006 -
>         Raw printers cannot use file: devices!
> scheduler is running
> system default destination: Minolta
> device for Minolta: /dev/lpt0
> Minolta accepting requests since Fri Jun 30 17:14:11 2006
> printer Minolta disabled since Fri Jun 30 17:14:11 2006 -
>         Raw printers cannot use file: devices!
> Minolta-47              rainer          195584   Fri Jun 30 17:14:11 20=
06
>
>
> -----------------------------------------------------------------------=
-------------------------------------------------------------------
> I found that the usb backend stalled here before actually doing any
> work. Before I've done any actual debugging of the backend, I suspect
> that it is being blocked on a status read attempt, though this is only
> my current guess.
>
> Here is a workaround:
>
> In printers.conf () you will probably find a line like this:
>
> DeviceURI usb:/dev/ulpt0
>
> change usb: to file:, so that it looks something like this:
>
> DeviceURI file:/dev/ulpt0
>
> Then restart cups. Cups will not read any status information from the
> printer, but at least it can print. Be warned about unknown side effect=
s. :)
>
> Jan-Espen Pettersen
>
>  =20
The problem is that read operations on usb printers might just
block/hang with no data from the printer (?). ulpt doesn't have
non-blocking I/O, so I've made a patch that simply times out read
operations, and disables further reads if it detects a blocking/stall
condition. It is possible that this breaks the back-channel, as I'm
unsure if we can expect a printer to send inbound data before we
actually write anything out?

It looks like there are similar problems with other backends? I've only
looked at the usb backend yet.

Jan-Espen Pettersen


--------------030401040401020208000605--

--------------enigBA648173365A5A7F6A220B8A
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.4 (FreeBSD)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFEpqPiH90qNYni6VoRAq+ZAJ9aDg1Og8FU40Td3xv1kZqGX+7iPgCgtCzm
ggqAkO7FLkQ/mGY+9PHnowU=
=MeVU
-----END PGP SIGNATURE-----

--------------enigBA648173365A5A7F6A220B8A--



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?44A6A3D5.9020607>