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SubjectRe: [PATCH 2/5] ide: ->ide_dma_clear_irq() -> ->clear_irq()
Hello.

Bartlomiej Zolnierkiewicz wrote:

>>>> * Rename ->ide_dma_clear_irq method to ->clear_irq
>>>> and move it from ide_hwif_t to struct ide_port_ops.
>>>>
>>>> * Move ->waiting_for_dma check inside ->clear_irq method.
>>>>
>>>> * Move ->dma_base check inside ->clear_irq method.
>>>>
>>>> piix.c:
>>>> * Add ich_port_ops and remove init_hwif_ich() wrapper.
>>>>
>>>> There should be no functional changes caused by this patch.
>>>>
>>>>
>>> Good. I think it's worth implementing this method in at least
>>> cmd64x.c which actually reads the IDE interrupt latch bits
>>> (independent from the DMA interrupt status) in the dma_test_irq()
>>> methods but never clears them, so the latches may reflect a
>>> non-current state of the IDE interrupt...
>>>
>> I forgot that it does clear them in its dma_end() methods (which I
>> myself have reworked :-).
>> It seems however that at least for SFF-8038 compatibles, it makes
>> sense to leave it that way since INTRQ might be asserted while BMIDE
>> interrupt bit is not, so the interrupt latch would need clearing even on
>> DMA timeout...
>>
>>> 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...
>>
>
> Or we can test for ->waiting_for_dma inside ->test_irq.
>

That also will do...

>>>> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>>>>
>>> Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
>>>
>> Not feeling sure about this patch -- ->waiting_for_dma probably
>> should've been left where it was...
>>
>
> Well, it doesn't change behavior and I think having ->clear_irq method
> independent from the transfer mode is a preffered approach.
>

But its implementations will have to depend on it anyway. And
clearing the IDE interrupt in general already depends on the transfer
mode -- the BMIDE interrupt which is a (delayed) reflection of INTRQ is
cleared implicitly by the dma_end() method -- except in at least sgiioc4
driver.
BTW, sgiioc4 seems another candidate for clear_irq() implementation
-- currently clearing is done implicitly by the read_status() method (I
don't quite understand why it clears DMA error interrupt there).
However, since there's no documentation, I'm not sure how the IDE
interrupt is latched by IOC4.

> Thanks,
> Bart
>

MBR, Sergei




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