[lkml]   [2019]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] lib/scatterlist: Provide a DMA page iterator
On Tue, Jan 15, 2019 at 03:24:55PM +0100, Christian König wrote:
> Yeah, indeed. Bounce buffers are an absolute no-go for GPUs.
> If the DMA API finds that a piece of memory is not directly accessible by
> the GPU we need to return an error and not try to use bounce buffers behind
> the surface.
> That is something which always annoyed me with the DMA API, which is
> otherwise rather cleanly defined.

That is exactly what I want to fix with my series to make
DMA_ATTR_NON_CONSISTENT more useful and always available:

With that you allocate the memory using dma_alloc_attrs with
DMA_ATTR_NON_CONSISTENT, and use dma_sync_single_* to transfer
ownership to the cpu and back to the device, with a gurantee that
there won't be any bouncing. So far the interest by the parties that
requested the feature has been rather lacklustre, though.

 \ /
  Last update: 2019-01-15 16:20    [W:0.114 / U:1.676 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site