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SubjectRe: [RFC][PATCH] move dma_mask into struct device
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arndb@de.ibm.com said:
> That does not sound like the right way to me. If you need to have the
> dma_mask for the Scsi_Host, you should store it in Scsi_Host itself. A
> struct device must never know about obscure architecture specific
> stuff like dma.

The SCSI host itself has no need of a DMA mask. What we need the mask for is
to set up the bounce limits for the block queue, we don't actually ever use it
again. Unfortunately, dma_mask isn't architecture specific, its a universal
property of the block queues used to determine when to bounce memory regions.

The dma_mask is a property of the connection of the Scsi_Host to the machine
bus, not of the Scsi_Host itself, so it does properly belong in the generic
device which is used to reflect machine bus attachments.

Think of it this way: we have two struct device's per SCSI host: one for the
actual HBA card or bus attachment, which contains all of the bus specific
pieces, and one for the host itself reflecting the fact that it is a bridge
from the machine bus to the scsi bus.

James



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