[PARPORT] Re: Need careless option in lp.c

Andrea Arcangeli (andrea@e-mind.com)
Thu, 1 Apr 1999 12:30:54 +0200 (CEST)

On Thu, 1 Apr 1999, Daniel Kobras wrote:

>"printer works fine with 2.0, no-go with 2.2 :-(". I managed to trace down
>the problem to SELEC never getting raised, which was fine (well, sort of)

Good spotting!

>- How can anything block in lp_check_status()?

Well I have to say that the new lp (that will be in 2.3) is been rewritten
quite a bit. The new lp via Tim's ieee code try to uses smarter ieee_1284
handshakes or the FIFO to do the handshake by hardware (and the hardware
handshake will probably check SELECT too) and as last resort it uses the
compat mode of the ieee_1284. And the compat mode of the ieee_1284 is a
standard and so if there is really buggy hardware out there will have to
increase the complexity of the 1284 code to handle some kind of
workaround (passing a parameter to the helper function for example).

>- Am I missing anything else?

I don't think.

>properly but doesn't raise SELEC]) to no end. The guy was not able to try
>a different cabling yet, I have to admit. The only thing that worked was

Well I am very interested to know if it's a cabling problem or not. If you
have a tester you can find the specs of the cable and check the signal
directly on the printer-port side. (if you don't have the specs I can
drive you)

And be quite, if careful is needed for the guy we'll change the kernel! ;)
The point is that so far _nobody_ ever used it and when I looked into I
noticed that the _unconditional_ check in lp_check_status() would have
blocked the printing anyway, so I thought it was been some old crappy hack
just to remove.

Let me know about the cable, in the meantime I'll send you a patch (note,
your patch was fine, but it was forcing all printers to not check SELECT
on the printer side and the SELECT check is needed to be allowed to start
the printing and _then_ poweron the printer, I learn this last thing by
experience with Tim if I remeber correctly ;).


Andrea Arcangeli

PS. CC to linux-parport because definitely on-topic ;)

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This archive was generated by hypermail 2.0b3 on Thu 01 Apr 1999 - 06:05:47 EST