[PARPORT] Re: parport irq handling v2

Philip Blundell (philb@gnu.org)
Mon, 31 Aug 1998 16:26:23 +0100

>The irq now is owned by the parport highlevel driver. This allow us to
>detect irq out of cad and avoiding the many request_irq() free_irq() done
>during the parport scheduling.

I still don't think this is the right way to solve the problem.

>what does it mean cad ? ;-)

I think it stands for `currently active device'.

>in parport_share.c will produce 0 asm code with parport_pc, if
>PARPORT_OTHERS is not #defined.

Having the lowlevel driver handle the interrupt would have no overhead
regardless of the setting of PARPORT_OTHERS. At the moment you have
parport_share handle the interrupt and make a call both down to parport_pc and
up to lp (or whatever). If parport_pc handled the interrupts directly it
would only need to call up to lp and parport_share would not be involved.

>I have not said this code has to go in 2.2 but at least I just implemented
>it ;-)

For 2.2 I guess it's slightly better than what we have now (fewer request/free
irq calls) and maybe it's a less invasive fix than doing it properly. Even if
we do put this patch into 2.2 I'd like to change to the other scheme for


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This archive was generated by hypermail 2.0b3 on Wed 30 Dec 1998 - 10:18:11 EST