Jeff Garzik wrote:
Mark Lord wrote:
Just about everything can do some form of DMA nowadays,
but regardless of that the sata_mv chipsets have errata
for PIO of anything more than a single sector.
In practice, I haven't managed to trigger the issue here,
but the errata descriptions indicate that it should be a major
issue for any volume of multi-sector PIO commands.
I need to review the state of PIO-multi, but IIRC it's not used by default.
We should be able to handle this errata without banning all PIO...
..
I'm not really all that worried about it.
But it affects *non multi* PIO as well -- anything that can generate
more than a single DRQ per command-issue.
So a READ_SECTORS or WRITE_SECTORS (pio) for anything more than
a single sector could do it, in theory.
If we *really* care, then I'll dig into it deeper in the next kernel.
It can be worked around in the IRQ handler, by taking great care in
the exact sequence of IRQ-arrival and DRQ-status checks.
Heck.. we might even have it right (by accident) today.
Cheers
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