[PATCH 3/4] dma-buf: add support for mapping with dma mapping attributes

Laura Abbott labbott at redhat.com
Sat Jan 19 16:50:41 UTC 2019


On 1/19/19 2:25 AM, Christoph Hellwig wrote:
> On Fri, Jan 18, 2019 at 10:37:46AM -0800, Liam Mark wrote:
>> Add support for configuring dma mapping attributes when mapping
>> and unmapping memory through dma_buf_map_attachment and
>> dma_buf_unmap_attachment.
>>
>> Signed-off-by: Liam Mark <lmark at codeaurora.org>
> 
> And who is going to decide which ones to pass?  And who documents
> which ones are safe?
> 
> I'd much rather have explicit, well documented dma-buf flags that
> might get translated to the DMA API flags, which are not error checked,
> not very well documented and way to easy to get wrong.
> 

I'm not sure having flags in dma-buf really solves anything
given drivers can use the attributes directly with dma_map
anyway, which is what we're looking to do. The intention
is for the driver creating the dma_buf attachment to have
the knowledge of which flags to use.

Thanks,
Laura


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