Re: sata_nv + ADMA + Samsung disk problem

[Jeff Garzik]

Allen Martin wrote:
> > The question I had for NVIDIA regarding this that I never got 
> > answered 
> > was, is there any reason why we would need a delay when switching 
> > between NCQ and non-NCQ commands on ADMA, and if not, is 
> > there any known 
> > cause that could cause the controller to get into this seemingly 
> > locked-up state?
>
> When switching from NCQ to non NCQ or vice versa you must make sure all
> outstanding commands are completed before issuing the new command.  The
> hardware doesn't do anything to prevent queued and non queued commands
> from going out on the wire at the same time which will certainly cause
> some drives to fail.

The software definitely provides that guarantee for all NCQ-capable 
controllers.

	Jeff



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