Re: [RFC PATCH] nForce4 ADMA with NCQ: It's aliiiive..

[Robert Hancock]

Mark Lord wrote:
> Robert Hancock wrote:
> > I also noticed that I'm still using the default 64KB libata 
> > dma_boundary value, this should be 4GB for ADMA mode (but fixed up 
> > back to the default if an ATAPI device is connected, same as with the 
> > DMA mask).
>
> Be careful of that.  The original PDC hardware for ADMA still had
> the "don't cross a 64KB boundary" requirement.
>
> Cheers

That is part of the ADMA spec - but in that case, how come the 
pdc_adma.c driver sets the dma_boundary in the SCSI host template to 
4GB? That seems wrong.

In any case, however, I really doubt the NVIDIA ADMA controller shares 
this limitation - they provide 32 bits for the region length (standard 
ADMA only has 16 bits), which wouldn't be very useful if you couldn't 
cross a 64KB boundary..

--
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@xxxxxxxxxxxxx
Home Page: http://www.roberthancock.com/

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