Re: [PATCH 02/02] sata_mv: warn on PIO with multiple DRQs

[Jeff Garzik <jgarzik@pobox.com>]

Mark Lord wrote:
> Chip errata sometimes prevents reliable use of PIO commands which involve
> more than a single DRQ (data request).  In normal operation, libata should
> not generate such PIO commands (uses DMA instead), but they could be sent
> in via SG_IO from userspace.
> 
> A full workaround might be to break up such commands into sequences
> of single DRQ ones, but that's just way too complex for something
> that doesn't normally happen in real life.
> 
> So, allow the attempt (it often works, despite the errata),
> but log the event for reference when somebody screams.
> 
> Signed-off-by: Mark Lord <mlord@pobox.com>


applied patches 1-2



> Tejun/Alan/Jeff:
> 
> We may also want a patch to prevent libata-eh from downshifting
> all the way to PIO on these chipsets, but I am not sure how to
> accomplish that from inside sata_mv.  Any suggestions?

Do we really want that?  Seems to me we need that for older bridged PATA 
devices attached to a SATA bridge.

	Jeff