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SubjectRe: 2.4.21-pre4: PDC ide driver problems with shared interrupts
Benjamin Herrenschmidt wrote:

>>Okay, I had to watch for it a bit longer and it turns out that the kernel PDC driver has a problem in this shared interrupt setup. When loads get high it seems to run into some timing problem which causes things like:
>>
>>Feb 4 01:02:22 admin kernel: hde: dma_intr: status=0xd0 { Busy }
>>
>>
>>
Since the busy bit is set, we know the drive must have received a
command. Since dma_intr thought the drive was not busy, an interrupt
must have snuck through between the command being issued and the dma
being started. I think in my original patch, I had the dma start
outside of the spinlock, that is a bug. The command to the controller
to start the dma must be inside of the spinlock.

I have not looked at 2.4.21-pre4 at all, so I could be entirely off base
here.

Ross

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