On 3 Apr 2023 17:47:50 +0200 Paul Cercueil paul@crapouillou.net
This function can be used to initiate a scatter-gather DMA transfer where the DMA addresses and lengths are located inside arrays.
The major difference with dmaengine_prep_slave_sg() is that it supports specifying the lengths of each DMA transfer; as trying to override the length of the transfer with dmaengine_prep_slave_sg() is a very tedious process. The introduction of a new API function is also justified by the fact that scatterlists are on their way out.
Given sg's wayout and conceptually iovec and kvec (in include/linux/uio.h), what you add should have been dma_vec to ease people making use of it.
struct dma_vec { dma_addr_t addr; size_t len; };
Signed-off-by: Paul Cercueil paul@crapouillou.net
v3: New patch
include/linux/dmaengine.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index c3656e590213..62efa28c009a 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -912,6 +912,11 @@ struct dma_device { struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)( struct dma_chan *chan, unsigned long flags);
- struct dma_async_tx_descriptor *(*device_prep_slave_dma_array)(
struct dma_chan *chan, dma_addr_t *addrs,size_t *lengths, size_t nb,enum dma_transfer_direction direction,unsigned long flags);
Then the callback looks like
struct dma_async_tx_descriptor *(*device_prep_slave_vec)( struct dma_chan *chan, struct dma_vec *vec, int nvec, enum dma_transfer_direction direction, unsigned long flags);