[PATCH v3 0/2] dmaengine: fsl-edma: Scatter/gather improvements

[Benoît Monin]

This series adds support for scatter/gather DMA transfers via dma_vec
and dynamic descriptor chaining to the Freescale eDMA controller driver.

The first patch implements the .device_prep_peripheral_dma_vec() callback,
enabling the DMA engine to accept an array of dma_vec structures. This
callback supports both regular and cyclic transfer modes.

The second patch introduces dynamic scatter/gather chaining, which allows
multiple DMA descriptors to be linked together without stopping the channel.
This optimization eliminates idle periods when back-to-back transfers are
submitted, improving throughput and reducing latency. The implementation
carefully preserves cyclic transfer semantics and respects hardware
constraints on platforms with split register layouts.

I tested it on the i.MX93. The dynamic scatter/gather chaining should
work with other eDMA controller with split register layout.

Signed-off-by: Benoît Monin <benoit.monin@xxxxxxxxxxx>
---
Changes in v3:
- Fix formatting errors reported by Frank Li.
- Add fsl_edma_tx_submit() to link the DMA transactions
  when they are submitted, not when they are prepared.
- Link to v2: https://patch.msgid.link/20260506-fsl-edma-dyn-sg-v2-0-66439cdd414e@xxxxxxxxxxx

Changes in v2:
- Drop the RFC prefix, as asked by Frank Li
- No code change
- Link to v1: https://patch.msgid.link/20260430-fsl-edma-dyn-sg-v1-0-4e0ecbe2df66@xxxxxxxxxxx

To: Frank Li <Frank.Li@xxxxxxx>
To: Vinod Koul <vkoul@xxxxxxxxxx>
Cc: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxx>
Cc: Frank Li <Frank.Li@xxxxxxxxxx>
Cc: imx@xxxxxxxxxxxxxxx
Cc: dmaengine@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx

---
Benoît Monin (2):
      dmaengine: fsl-edma: Implement device_prep_peripheral_dma_vec
      dmaengine: fsl-edma: Support dynamic scatter/gather chaining

 drivers/dma/fsl-edma-common.c | 197 ++++++++++++++++++++++++++++++++++++++++--
 drivers/dma/fsl-edma-common.h |   4 +
 drivers/dma/fsl-edma-main.c   |   2 +
 drivers/dma/fsl-edma-trace.h  |   5 ++
 4 files changed, 202 insertions(+), 6 deletions(-)
---
base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
change-id: 20260428-fsl-edma-dyn-sg-960731e37da2

Best regards,
--  
Benoît Monin, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com