[coreboot] [patch] ACPI on m57sli v1.0 - parport interrupt driven

Harald Gutmann harald.gutmann at gmx.net
Mon Jul 6 19:36:35 CEST 2009

On Saturday 04 July 2009 11:02:36 Harald Gutmann wrote:
> On Thursday 02 July 2009 23:26:34 Peter Stuge wrote:
> > Harald Gutmann wrote:
> > > > Is the port interrupt-driven, or polling, on your system, Andreas?
> > >
> > > Here on my system it says also polling, like on Andreas system.
> > > What is the difference between interrupt driven and polling?
> >
> > Interrupt driven means the port has an interrupt assigned to it, and
> > that communication over the port is event based.
> >
> > Polling means there is a timer running in the kernel which will check
> > the port for activity every few milliseconds or something.
> >
> > > On vendor bios it is interrupt-driven.
> > > Is an ACPI part missing to get it interrupt driven?
> >
> > I think so, yes.
> So, I've added the missing ACPI part, but it seems that some more work is
> needed to get parport interrupt driven working.
I just did a mistake and set no address in the IO Section.

There's already another patch on the list (which was filtered by my spam-filter, 
and therefore I did the job again).
The difference between my patch, and the one from Andreas are minimal, but I 
added the ECP device which is necessary to get Parport full functional 
(hopefully I did everything correct, as I can't test this without Parport 

The attached patch activates changes the LPT port from polling to interrupt-
driven, and should be fine.

Signed-off-by: Harald Gutmann <harald.gutmann at gmx.net>

Kind regards,

> The dmesg output changes a little bit, and also mentions IRQ7, but lp0 is
> still noticed as polling:
> [  745.974254] parport_pc 00:04: reported by Plug and Play ACPI
> [  745.974371] parport0: PC-style at 0x378 (0x778) [PCSPP,TRISTATE]
> [  746.104129] parport0: irq 7 detected
> [  751.914593] ppdev: user-space parallel port driver
> [  770.953504] lp0: using parport0 (polling).
> I think that it is necessary to set some irq bit to get it working fine.
> This idea is from the vendors dsdt.asl [1] and the LPT1 (starting at line
> 5374) section of it.
> Looking at that part there is something noticed about INTR which could be
> the IRQ bit I assume that this is needed.
> Can anyone help me out here a little bit?
> [1] http://coreboot.pastebin.com/f3e965943
> >
> > //Peter

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