USB driver uses backchannel, which doesn't work on NetBSD

[michaelrsweet]

Version: 1.2.8
CUPS.org User: gdt

With cups 1.2.10 on NetBSD (i386, 4.0_BETA2), printing to an HP 1320 attached via USB fails. It works with 1.1.23. NetBSD's ulpt(4) driver does not support reading from USB printers, but because use_bc=1, cups tries to read and the usb driver hangs when no data is forthcoming.

With the attached patch (which is in pkgsrc/print/cups), I was able to print a test page.

Fixing this correctly is tricky; one can't assume a printer is present at configure time (especially for pkgsrc which does bulk builds for binary packages). NetBSD may in the future support the backchannel on ulpt(4). So probably the best approach is to read from the device, but with a timeout, and essentially fall back to use_bc=0 if nothing is read.

[michaelrsweet]

CUPS.org User: mike

Fixed in Subversion repository.

I also changed open_device() so that it only opened the device file for writing...

[michaelrsweet]

"patch-au":

$NetBSD: patch-au,v 1.6 2007/04/02 12:11:01 gdt Exp $

--- backend/usb-unix.c.orig 2007-02-20 08:41:07.000000000 -0500
+++ backend/usb-unix.c
@@ -90,6 +90,11 @@ print_device(const char uri, / I - De
strcasecmp(hostname, "Konica Minolta") &&
strcasecmp(hostname, "Minolta");

+#ifdef NetBSD

• /* XXX Use configure test to see if reading from ulpt(4) works. */
• use_bc = 0;
  +#endif

if ((device_fd = open_device(uri, &use_bc)) == -1)
{
if (getenv("CLASS") != NULL)

[michaelrsweet]

"str2324.patch":

Index: usb-unix.c

--- usb-unix.c (revision 6436)
+++ usb-unix.c (working copy)
@@ -80,7 +80,16 @@

do
{
+#ifdef NetBSD
/*

• * NetBSD's ulpt driver currently does not support the
• * back-channel...
• */

• use_bc = 0;

+#else

• /*

• Disable backchannel data when printing to Brother, Canon, or

• Minolta USB printers - apparently these printers will return

• the IEEE-1284 device ID over and over and over when they get
  @@ -91,6 +100,7 @@
  strcasecmp(hostname, "Canon") &&
  strcasecmp(hostname, "Konica Minolta") &&
  strcasecmp(hostname, "Minolta");
  +#endif /* NetBSD */

  if ((device_fd = open_device(uri, &use_bc)) == -1)
  {
  @@ -519,7 +529,12 @@
  }
  #else
  {

• if ((fd = open(uri + 4, O_RDWR | O_EXCL)) < 0)

• if (use_bc)

•  fd = open(uri + 4, O_RDWR | O_EXCL);
  

• else

•  fd = -1;
  

• if (fd < 0)
  {
  fd = open(uri + 4, O_WRONLY | O_EXCL);
  *use_bc = 0;