On Mon, Jun 24, 2019 at 03:23:08PM +0100, Vladimir Murzin wrote: > On 6/14/19 3:44 PM, Christoph Hellwig wrote: > > The arm-nommu DMA code supports DMA_ATTR_NON_CONSISTENT allocations, but > > does not provide a cache_sync operation. This means any user of it > > will never be able to actually transfer cache ownership and thus cause > > coherency bugs. > > By the way, Documentation/DMA-attributes.txt doesn't specify cache_sync() as > requirement for DMA_ATTR_NON_CONSISTENT it only states that it is responsibility > of the driver to have all the correct and necessary sync points. True. dma_cache_sync has always been a rather odd interface, as it doesn't specify in what direction we need to sync and doesn't participate in our ownership protocol. So my mid-term plan is to kill it off and replace it with the existing dma_sync_* helpers. This series is the first step towards that.
