Re: [PATCH 1/3 v3] dma: document dma_{un}map_{single|sg}_attrs() interface

akepner
2008-03-20T00:42:36Z

On Fri, Mar 14, 2008 at 03:30:29PM +1100, Michael Ellerman wrote:
>
> I like this better, sorry to keep nitpicking, but just a few comments
> below ..

Comments are appreciated.

> ...
> You say a "DMA to a memory region with the DMA_ATTR_BARRIER attribute
> forces all pending DMA writes to complete". Does it force _all_ DMA
> writes to complete, or just writes to the region, or just writes coming
> from devices? What if something is writing to a device?
>

Yes, forces all writes to complete (as others have already said).

> Does DMA_ATTR_BARRIER have any effect on reads?
>

No, changed the name to DMA_ATTR_WRITE_BARRIER to emphasize this.

--
Arthur