[Linux-parport] parport data_reverse patch

Steve deRosier steve at cozybit.com
Tue Mar 2 20:24:42 EST 2010


I am having some trouble with parallel ports with VMWare server
running on Ubuntu.

When you try to use the parallel port, it won't work and the dmesg
output will show something like:

[78100.870664] parport0 (ppdev0): use data_reverse for this!
[78106.513997] parport0 (ppdev0): use data_reverse for this!
[78181.921856] parport0 (ppdev0): use data_reverse for this!

A few searches came up with information leading to the following code
work around:

--- include/linux/parport_pc.h.orig     2009-12-03 11:27:03.000000000 -0800
+++ include/linux/parport_pc.h  2009-12-02 12:24:53.000000000 -0800
@@ -144,7 +144,7 @@
 static __inline__ void parport_pc_data_reverse (struct parport *p)
-       __parport_pc_frob_control (p, 0x20, 0x20);
+//     __parport_pc_frob_control (p, 0x20, 0x20);
 static __inline__ void parport_pc_data_forward (struct parport *p)

This solves our current problem, but we'd prefer to create a patch
that can go into the kernel tree.  Maybe an appropriate approach would
be to make this a module variable, with the default being the existing
behavior.  If there's other ideas, or this has been solved, I'd love
to hear about it.

If you'd like me to prepare a patch, I'd be happy to.  Should I send
it to the list?

- Steve

More information about the Linux-parport mailing list