On Wed, Aug 19, 2020 at 04:22:29PM +0200, Tomasz Figa wrote:
FWIW, I asked back in time what the plan is for non-coherent allocations and it seemed like DMA_ATTR_NON_CONSISTENT and dma_sync_*() was supposed to be the right thing to go with. [2] The same thread also explains why dma_alloc_pages() isn't suitable for the users of dma_alloc_attrs() and DMA_ATTR_NON_CONSISTENT.
AFAICS even back then Christoph was implying getting rid of NON_CONSISTENT and *replacing* it with something streaming-API-based -
That's not how I read his reply from the thread I pointed to, but that might of course be my misunderstanding.
Yes. Without changes like in this series just calling dma_sync_single_* will break in various cases, e.g. because dma_alloc_attrs returns memory remapped in the vmalloc space, and the dma_sync_single_* implementation implementation can't cope with vmalloc addresses.