Re: [parisc-linux] Untested port of parisc_device to generic device interface

Grant Grundler (grundler@dsl2.external.hp.com)
Wed, 13 Nov 2002 13:37:09 -0700


"J.E.J. Bottomley" wrote:
> Actually, I think dma_mask and consistent memory are orthogonal problems.

No. consistent memory needs to be reachable by the device as well.
dma_mask constrains which memory pci_alloc_consistent() can use.

> dma_masks are used by the I/O subsystem to determine whether direct DMA to a
> memory region containing an I/O buffer is possible or whether it has to be
> bounced. Consistent memory is usually allocated for driver specific
> transfers. The I/O subsystem doesn't usually require the actual I/O buffers
> to be in consistent memory.

right.

grant
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