On 02-07-21, 15:23, Adrian Larumbe wrote:

On 01.06.2021 15:59, radhey pandey wrote:

quoted

On Fri, Apr 23, 2021 at 10:51 PM Vinod Koul [off-list ref] wrote:

quoted

On 23-04-21, 15:51, Lars-Peter Clausen wrote:

quoted

On 4/23/21 3:24 PM, Vinod Koul wrote:

quoted

On 23-04-21, 11:17, Lars-Peter Clausen wrote:

quoted

It seems to me what we are missing from the DMAengine API is the equivalent
of device_prep_dma_memcpy() that is able to take SG lists. There is already
a memset_sg, it should be possible to add something similar for memcpy.

You mean something like dmaengine_prep_dma_sg() which was removed?

Ah, that's why I could have sworn we already had this!

Even at that time we had the premise that we can bring the API back if
we had users. I think many have asked for it, but I havent seen a patch
with user yet :)

Right.  Back then we had also discussed bringing the dma_sg API
but the idea was dropped as we didn't had a xilinx/any consumer
client driver for it in the mainline kernel.

I think it's the same state now.

Would it be alright if I brought back the old DMA_SG interface that was removed
in commit c678fa66341c?  It seems that what I've effectively done is
implementing the semantics of that API call under the guise of
dma_prep_slave. However I still need mem2mem SG transfer support on CDMA, which
seems long gone from the driver, even though the HW does offer it.

If people are fine with it I can restore that interface and CDMA as the sole consumer.

I guess I should start putting this regularly now! Yes it is okay to
bring dma sg support, provided
1. We have a user
2. the sematics of how that api works is well defined. Esp in the case where is src_sg and dstn_sg are different

Also, I would not accept patches which implement this in guise of a
different API.

Thanks

-- 
~Vinod

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