Messages in this thread | | | Subject | Re: [RFC][PATCH] move dma_mask into struct device | Date | Sat, 16 Nov 2002 10:33:44 -0500 | From | "J.E.J. Bottomley" <> |
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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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