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Date:      Mon, 29 Nov 1999 00:21:56 -0700
From:      Warner Losh <imp@village.org>
To:        new-bus@freebsd.org
Subject:   Interrupt irq activation question
Message-ID:  <199911290721.AAA90820@harmony.village.org>

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In my pccard_nbk I turned on interrupts when the IRQ resource was
activated.  In my newconfig pccard code, I'd like to do the same
thing.  I notice that the NetBSD code base turns them on/off in its
intr_establish/intr_disestablish routines, which basically map to our
bus_intr_setup and bus_intr_teardown methods.  It got me thinking.  Do 
I want to do them in the activate phase, or later in the establish
phase.

The advantage of doing them in the activate phase is that devices like 
sio that try to probe for the interrupt used can activate the
interrupt w/o registering an actual interrupt handler for the device
and somehow check to see if that interrupt is responding.

The advantage for doing them in the setup/teardown methods is that I
suppose this violates POLA less and might result in fewer stray
interrupts.

Any opinions on the matter?  I seem to recall that Doug Rabson once
told me activate/deactivate was the architecturally pure way to do
this.  I cannot find his email that told me this, so I thought I'd ask 
here in an archived forum.

Warner


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