On Fri, Jan 02, 2015 at 05:01:42PM +0530, Mayuresh Chitale wrote: 1st things stop TOP posting, this is not good email etiquette... > The DMA engine is actually a part of a PCI root complex and uses > memory mapped FIFOs for both sides i.e AXI and PCI and we need to > program memory mapped queues for both AXI side and PCI side. Its > possible that there could be multiple elements from AXI side that need > to be transferred to multiple elements to PCI side or vice-versa > provided that the total length on both sides is equal. I see there is > the device_prep_dma_sg api but it appears to me that is only intended > to be used for async operations. Is that correct? the FIFO will have constant address or will it increment/decrement? -- ~Vinod > > On Fri, Jan 2, 2015 at 4:51 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: > > On 01/02/2015 12:09 PM, Mayuresh Chitale wrote: > >> > >> Yes. That is correct. > > > > > > Ok, but please explain in detail what exactly your use case is for this for > > slave-device DMA. For a device you usually have either a dedicated DMA port > > to which the DMA controller is directly connected or a memory mapped FIFO. > > So there really is only one source or destination when reading from a device > > or writing to a device. > > > > > >> > >> Thanks, > >> Mayuresh. > >> > >> On Fri, Jan 2, 2015 at 4:39 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> > >> wrote: > >>> > >>> On 01/02/2015 12:03 PM, Mayuresh Chitale wrote: > >>>> > >>>> > >>>> Hi, > >>>> > >>>> I am working on a slave dma driver that supports scatter-gather > >>>> operation. However looking at APIs in dmaengine.h I see that the > >>>> device_prep_slave_sg supports only many to one transfer. Is there any > >>>> API that can be used to support many to many transfers for slave dma? > >>> > >>> > >>> > >>> What do you mean by many to many? Many sources to many destinations? > >>> > >>> - Lars > >>> > > > -- > To unsubscribe from this list: send the line "unsubscribe dmaengine" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
