Messages in this thread | | | From | "David Campbell" <> | Date | Sun, 1 Feb 1998 07:47:17 +0000 | Subject | Re: [PARPORT] Re: problems with parallel port IRQ detection |
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> To: "Jerod E. Tufte" <jet@jolt.com> > Cc: linux-kernel@vger.rutgers.edu, linux-parport@torque.net > Subject: [PARPORT] Re: problems with parallel port IRQ detection > Date: Sat, 31 Jan 1998 00:07:52 +0000 > From: Philip Blundell <Philip.Blundell@pobox.com>
> >does anyone have a solution for this? in 2.0.x, both my palmtop PC110 > >and my desktop machine have no problems using PLIP. if I boot either > >to 2.1.x (I've tried for most x>60) PLIP reports detecting IRQ 8 for > >the first port (should be 0x378/IRQ7) on both of them. trying to use > >modules for all the parallel port stuff and plip and forcing the irq > >as an option to insmod doesn't seem to work either. What useful > >information can I report to help the parallel port gurus to track this > >down? > > The problem is that the ECP/EPP code is too smart about detecting IRQs. David > Campbell is probably the man to fix it. If it can't be made to work reliably > then that autodetect should be taken out.
I have a few ideas to fix this problem, however I am extremely busy at work for the next two weeks.
When I wrote the original code it was to handle the situation of IRQ sharing (I have a machine with full port count 3 LPT + 4 COM). This required a slightly different IRQ probing scheme to that used previously in Linux (which assumes that each IRQ is mapped to at most one device driver).
Rumor has it that with *some* ASUS main boards (I am most likely to be wrong here) that if the onboard PS/2 mouse port is disabled then the IRQ is stuck active.
What needs to be done is to adjust the IRQ code to either: ============================================================= a) Use conventional Linux IRQ probing techniques. b) Check for IRQs which are either stuck active or periodically active (timer). Then mask these IRQs from the results.
I favour method b (flame me if you like, it is bushfire season here in Asutralia), as the average PC does not have enough IRQs for all the *useful* hardware => 2 IDE, 2 serial, 1 parallel, 1 network card, 1 sound card, 1 video card + several other system devices [keyboard, timer, x87 interupt] THEN start adding SCSI cards.....
Using the current Linux model it is impossible to have a SoundBlaster card AND use the IRQ for printing. (Arrgg!!!)
I will spend some time today (Sunday, 1st Feb) and grab the latest 2.1.x kernel and make the necessary mods to the IRQ detection. A patch will be distributed via the parport mailing list.
David Campbell ======================================================= campbell@torque.net (Parallel port device related mail) dcampbel@p01.as17.honeywell.com.au (For all other mail)
"All parallel ports are equal - Some are more equal than others"
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