Re: ->ack_intr in m68k IDE drivers [was: Re: [PATCH 2/5] ide: ->ide_dma_clear_irq()-> ->clear_irq()]

From: Sergei Shtylyov
Date: Fri May 22 2009 - 15:18:53 EST


Bartlomiej Zolnierkiewicz wrote:

It may also be worth considering turning this method into test-and-clear, so that we can get the actual IDE interrupt state on the chips that implement this...

Probably might add the test_irq() method to be called on !hwif->waiting_for_dma. Cleraing the status at once seems impractical...

Yet this seems what ack_intr() method is doing already...
What it does is testing IRQ status and "acknowledging" it (the semantics of "acknowledge" is not clear to me, yet it seems that it's clearing the interrupt latch in the drivers where it's implemented). And the call site of ack_intr() method corresponds to where test_irq() should have been called, so it seems we don't need yet another method and probably didn't even need clear_irq() method in the first place?..

They have different goals -- the main purpose of ack_intr() (despite its name)
seems to be testing whether the IRQ is ours,

It does clear some interrupt bit if it sees that IRQ is ours too, hence the name.

OTOH in clear_irq() we know that
already and we just want to clear the pending IRQ status.

There seems to be duplication of functionality b/w ack_intr() and clear_irq() now...

So I'm not sure if unification is desirable... though some improvements are
definitely possibly there (less confusing naming at least)...

Bart, could you clarify about how ack_intr() is supposed to work?

Good question, m68k list would be the best place to look for an answer..

Well, I seem to have been able to infer it from the code...

MBR, Sergei
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