Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails

From: Sinan Kaya
Date: Tue Nov 10 2015 - 15:26:21 EST

On 11/10/2015 3:05 PM, James Bottomley wrote:
OK, you don't seem to be understanding the problem: the Altix isn't a
LSI card, it was a SGI platform.

Got it.

It was the platform where we first
discovered the issue that a lot of storage cards didn't work because it
by default had no memory below 4GB. The reason coherent masks were
introduced was initially so the Altix could manufacture and manage a
region of memory in the lower 4GB region and we would guarantee to make
allocations from it so the storage cards would then work on that

I can't fix the issue if the card cannot do 64 bit DMA when IOMMU is not there. I need IOMMU enabled all the time for this card.

Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
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