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DateWed, 02 Jan 2008 13:57:41 -0500
FromJeff Garzik <>
SubjectRe: sata_nv + ADMA + Samsung disk problem
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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