HP LaserJet 1010 apparent bi-directional communication problems (with ulpt)

[Peter van Heusden]

Hi everyone

I just sent in PR usb/112944, a patch to force uni-directional
communication for the HP LaserJet 1010 (as recommended by Eygene
Ryabinkin), since bi-di doesn't seem to work. Since I wrote this patch,
I've heard that the Samsung ML-4600 laser (product ID 0x3004) also
doesn't work properly in bi-di mode, at least with CUPS. What happens is
that CUPS has a select() on the /dev/ulpt, and listens to see if there
is data to read - when select() indicates that there is, CUPS reads, but
hangs on read. Of course, forcing uni-direction communication fixes this
problem.

I'm not sure if there is a deeper underlying problem here, so I'm not
sure if this patch is appropriate? Ulrich Spoerlein
<uspoerlein at gmail.com> mentioned that the new USB stack (by HPS) works
with the ML-4600, btw.

Peter
pvh at wfeet.za.net