On Wed, Feb 19, 2025 at 04:38:47PM +0530, Devendra K Verma wrote:
+ Niklas (who also looked into the MEMCPY for eDMA)
> Added the simple or non-linked list DMA mode of transfer.
>
Patch subject and description are also simple :) You completely forgot to
mention that you are adding the DMA_MEMCPY support to this driver. That too only
for HDMA.
> Signed-off-by: Devendra K Verma <devverma@xxxxxxx>
> ---
> drivers/dma/dw-edma/dw-edma-core.c | 38 +++++++++++++++++
> drivers/dma/dw-edma/dw-edma-core.h | 1 +
> drivers/dma/dw-edma/dw-hdma-v0-core.c | 59 ++++++++++++++++++++++++++-
> 3 files changed, 97 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index 68236247059d..bd975e6d419a 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -595,6 +595,43 @@ dw_edma_device_prep_interleaved_dma(struct dma_chan *dchan,
> return dw_edma_device_transfer(&xfer);
> }
>
> +static struct dma_async_tx_descriptor *
> +dw_edma_device_prep_dma_memcpy(struct dma_chan *dchan,
> + dma_addr_t dst,
> + dma_addr_t src, size_t len,
> + unsigned long flags)
> +{
> + struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
> + struct dw_edma_chunk *chunk;
> + struct dw_edma_burst *burst;
> + struct dw_edma_desc *desc;
> +
> + desc = dw_edma_alloc_desc(chan);
> + if (unlikely(!desc))
> + return NULL;
> +
> + chunk = dw_edma_alloc_chunk(desc);
> + if (unlikely(!chunk))
> + goto err_alloc;
> +
> + burst = dw_edma_alloc_burst(chunk);
> + if (unlikely(!burst))
> + goto err_alloc;
> +
> + burst->sar = src;
> + burst->dar = dst;
Niklas looked into adding MEMCPY support but blocked by the fact that the
device_prep_dma_memcpy() assumes that the direction is always MEM_TO_MEM. But
the eDMA driver (HDMA also?) only support transfers between remote and local
DDR. So only MEM_TO_DEV and DEV_TO_MEM are valid directions (assuming that we
call the remote DDR as DEV).
One can also argue that since both are DDR addresses anyway, we could use the
MEM_TO_MEM direction. But that will not help in identifying the unsupported
local to local and remote to remote transfers.
I haven't referred the HDMA spec yet, but does HDMA support the above case also?
- Mani
--
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