| 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 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);
Hi Hillf, Le mardi 04 avril 2023 à 09:59 +0800, Hillf Danton a écrit : > 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; > }; Well it's not too late ;) Thanks for the feedback. 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); > > 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);
Am 04.04.23 um 09:42 schrieb Paul Cercueil: > Hi Hillf, > > Le mardi 04 avril 2023 à 09:59 +0800, Hillf Danton a écrit : >> 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; >> }; > Well it's not too late ;) Yeah adding that is pretty much the job I have on my TODO list for quite some time. I wouldn't mind if you start adding that and provide helper functions in DMA-buf to convert from/to an sg_table. This way we can migrate the interface over to a new design over time. Regards, Christian. > > Thanks for the feedback. > > 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); >> 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);
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(+)