Alan Cox wrote:
port freeze during an interrupt while DMA is active causes a bus error
to be thrown when the ata_check_status call fires. I cannot reproduce
this on x86. I assume it handles the taskfile read error differently.
I hit this problem with the HPT343 (which locks the bus if you do this).
For other devices where you get a PCI abort it is usually the case that
x86 platforms ignore them while on many other platforms they produce
exceptions.
In general I think we need to be sure all the core code paths stop DMA
before poking in the taskfile (other than the basic IRQ check which we
can't avoid)
I really think we are currently getting the ordering wrong, by calling
ata_qc_complete() before we call the ->freeze() hook.
You can see sata_promise had problems with this, which led us to add DMA
disabling in pdc_freeze()
But I think more generally, we seem to be missing a DMA-disable upon
freeze, across a wide variety of controllers.
Jeff
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