On Mon, Jun 29, 2020 at 03:03:56PM +0200, Christoph Hellwig wrote:

Add a new API to check if calls to dma_sync_single_for_{device,cpu} are
required for a given DMA streaming mapping.

+::
+
+	bool
+	dma_need_sync(struct device *dev, dma_addr_t dma_addr);
+
+Returns %true if dma_sync_single_for_{device,cpu} calls are required to
+transfer memory ownership.  Returns %false if those calls can be skipped.

Hi Christoph -

Thie call above is for a specific dma_addr.  For correctness, would I
need to check every addr, or can I assume that for a specific memory
type (pages returned from malloc), that the answer would be identical?
-- 
Jonathan