Re: [PARPORT] Re: ftape with Trakker parallel port

[Jeremy Elson]

"Jochen Hoenicke" writes:
>It is not easy to autodetect the irq number for parallel ports.  AFAIK
>only ECP makes it possible to detect the interrupt.  You should always
>use the "irq=" option of parport_pc.

I have noticed that with some parallel port hardware (when in normal
bi-dir PS/2 mode), a single spurious interrupt is generated when I
turn on the IRQ-enable bit in the control register.  I have never
found any documentation of this "feature" but I think it may be
there to aid in IRQ autodetection.  In particular I know my Dell
Optiplex GX1 at work does this.

I don't think the kernel tries using this trick to detect IRQ
interrupts currently... I keep meaning to write a patch.

-Jer