Re: sata_nv and dynamically changing DMA mask?

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From: Robert Hancock
Date: Tuesday, October 30, 2007 - 4:59 pm

Alan Cox wrote:

Indeed we do call ata_port_start from nv_adma_port_start, which calls 
dmam_alloc_coherent to allocate the SFF PRD table. Since the DMA mask is 
64-bit, this could indeed be allocated above 4GB which would be bad.

I suppose what we could do is just not call ata_port_start there, but 
move it into nv_adma_slave_config and call it when going into non-ADMA 
mode. We'd have to drop the DMA mask down to 32-bit first as well as 
setting blk_queue_bounce_limit though, which is one of my questions, is 
this OK to do?


The only cases where that could happen are for polling DMA commands 
(which I presume we never do) or where result taskfile is requested. The 
latter could be a problem for ATA passthrough commands using DMA, I 
suppose.. Question is what we can do about it.. We have to switch out of 
ADMA mode to read a result taskfile. I guess that's not really a problem 
unless somebody starts issuing NCQ commands via ATA pass-through. Do we 
allow that?
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Messages in current thread:
sata_nv and dynamically changing DMA mask?, Robert Hancock, (Mon Oct 29, 9:17 pm)
Re: sata_nv and dynamically changing DMA mask?, Alan Cox, (Tue Oct 30, 3:05 am)
Re: sata_nv and dynamically changing DMA mask?, Robert Hancock, (Tue Oct 30, 4:59 pm)