Re: ncr53c8xx + tulip IRQ sharing

Rogier Wolff (R.E.Wolff@BitWizard.nl)
Mon, 16 Feb 1998 08:38:50 +0100 (MET)

Gerard Roudier wrote:
>
> IMHO, this is not an hardware limitation, but a Linux limitation,
> probably for some performances considerations.

> If you hack a SCSI driver regarding request_interrupt flags, you
> just break some assumption on interrupts state for this drivers.
> It will be at least required to add some code to disable interrupts
> at interrupt routine entry point and to restore them on exit from
> this routine.

No. Linux guarantees that YOUR interrupt will not occur. This means
that you have free reign about your own device (the ncr8xx). However
if you cannot tolerate being interrupted for a few microseconds, (e.g.
if the device has a microsecond timeout after writing a "low word")
you can opt for running the whole interrupt routine with interrupts
off to keep things "consistent".

I don't think that the NCR is that badly designed, and that running
with interrupts enabled (all other interrupts) is acceptable.

Roger.

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