| Message ID | 20230403154800.215924-2-paul@crapouillou.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iio: new DMABUF based API, v3 | expand |
On 03-04-23, 17:47, Paul Cercueil wrote: > 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. Do we need a new API for this? why not use device_prep_interleaved_dma? > > 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); > struct dma_async_tx_descriptor *(*device_prep_slave_sg)( > struct dma_chan *chan, struct scatterlist *sgl, > unsigned int sg_len, enum dma_transfer_direction direction, > @@ -974,6 +979,17 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single( > dir, flags, NULL); > } > > +static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_dma_array( > + struct dma_chan *chan, dma_addr_t *addrs, size_t *lengths, > + size_t nb, enum dma_transfer_direction dir, unsigned long flags) > +{ > + if (!chan || !chan->device || !chan->device->device_prep_slave_dma_array) > + return NULL; > + > + return chan->device->device_prep_slave_dma_array(chan, addrs, lengths, > + nb, dir, flags); > +} > + > static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg( > struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, > enum dma_transfer_direction dir, unsigned long flags) > -- > 2.39.2
Hi Vinod, Le mercredi 12 avril 2023 à 22:53 +0530, Vinod Koul a écrit : > On 03-04-23, 17:47, Paul Cercueil wrote: > > 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. > > Do we need a new API for this? why not use > device_prep_interleaved_dma? I admit that I discarded the interleaved DMA without trying it, because reading the doc, e.g. the one for "struct data_chunk", It looked like it was not usable for when the DMA addresses are scattered in memory; it assumes that the following DMA addresses will always come after the previous one. Cheers, -Paul > > > > 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); > > struct dma_async_tx_descriptor *(*device_prep_slave_sg)( > > struct dma_chan *chan, struct scatterlist *sgl, > > unsigned int sg_len, enum dma_transfer_direction > > direction, > > @@ -974,6 +979,17 @@ static inline struct dma_async_tx_descriptor > > *dmaengine_prep_slave_single( > > dir, flags, > > NULL); > > } > > > > +static inline struct dma_async_tx_descriptor > > *dmaengine_prep_slave_dma_array( > > + struct dma_chan *chan, dma_addr_t *addrs, size_t *lengths, > > + size_t nb, enum dma_transfer_direction dir, unsigned long > > flags) > > +{ > > + if (!chan || !chan->device || !chan->device- > > >device_prep_slave_dma_array) > > + return NULL; > > + > > + return chan->device->device_prep_slave_dma_array(chan, > > addrs, lengths, > > + nb, dir, > > flags); > > +} > > + > > static inline struct dma_async_tx_descriptor > > *dmaengine_prep_slave_sg( > > struct dma_chan *chan, struct scatterlist *sgl, unsigned > > int sg_len, > > enum dma_transfer_direction dir, unsigned long flags) > > -- > > 2.39.2 >
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); struct dma_async_tx_descriptor *(*device_prep_slave_sg)( struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, enum dma_transfer_direction direction, @@ -974,6 +979,17 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single( dir, flags, NULL); } +static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_dma_array( + struct dma_chan *chan, dma_addr_t *addrs, size_t *lengths, + size_t nb, enum dma_transfer_direction dir, unsigned long flags) +{ + if (!chan || !chan->device || !chan->device->device_prep_slave_dma_array) + return NULL; + + return chan->device->device_prep_slave_dma_array(chan, addrs, lengths, + nb, dir, flags); +} + static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg( struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, enum dma_transfer_direction dir, unsigned long flags)
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. Signed-off-by: Paul Cercueil <paul@crapouillou.net> --- v3: New patch --- include/linux/dmaengine.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)