Occasional IDE lost interrupts

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

Hi Bart !

That seem to be a new problem though I can't tell for sure when it
started. I've had reports from users for some time now of
"occasional" (once in a while, maybe once a day) lost interrupts on the
mac hard disk. I have about 30 days uptime and just saw a similar one in
my log. It happen during a disk access storm (apt-get upgrade :).

The problem when this happen is that I just lost DMA which is fairly
annoying. Users are not supposed to understand the magic of hdparm
-d1 /dev/hda and that shouldn't happen anyways...

Do you have any clue of what can be going on ? The IDE pmac driver has
not changed for a long time and I think that problem is fairly new
(maybe 2.6.12 ? not sure, first time I actually see it unless it's
unrelated and my disk is actually dying).

Shouldn't we have some more retry before giving up on DMA ?

Regards,
Ben.

[432796.162593] ide-pmac lost interrupt, dma status: 8480
[432796.162606] hda: lost interrupt
[432796.162613] hda: dma_intr: status=0xd0 { Busy }
[432796.162619]
[432796.162622] ide: failed opcode was: unknown
[432796.162632] hda: DMA disabled
[432796.262581] ide0: reset: success