On 01/02/2015 12:31 PM, Mayuresh Chitale wrote:
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?
It's probably the closest to what you want. But it is for copying from
memory region to memory region so the addresses will be incremented. But if
I understand you correctly in your case you have memory mapped FIFOs so a
fixed addresses. I think you'll have to extend the dmaengine API to support
this kind of interleaved FIFO copy.
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
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