[RFC PATCH 0/3] net: axienet: Introduce dmaengine support

[Radhey Shyam Pandey]

The axiethernet driver now uses the dmaengine framework to communicate
with the xilinx DMAengine driver(AXIDMA, MCDMA). The inspiration behind
this dmaengine adoption is to reuse the in-kernel xilinx dma engine 
driver[1] and remove redundant dma programming sequence[2] from the 
ethernet driver. This simplifies the ethernet driver and also makes
it generic to be hooked to any complaint dma IP i.e AXIDMA, MCDMA 
without any modification.

This initial version is a proof of concept and validated with a ping test
on an AXI ethernet subsystem 1G + xilinx AXI DMA design. There is an
anticipated performance impact due to the adoption of the dmaengine 
framework. The plan is to revisit it once all required functional 
features are implemented.

The dmaengine framework was extended for metadata API support during the
axidma RFC[3] discussion. However, it still needs further enhancements to
make it well suited for ethernet usecases. The ethernet features i.e
ethtool set/get of DMA IP properties, ndo_poll_controller, trigger
reset of DMA IP from ethernet are not supported (mentioned in TODO)
and it requires follow-up discussion and dma framework enhancement.

Comments, suggestions, thoughts to implement remaining functional
features are very welcome!

[1]: https://github.com/torvalds/linux/blob/master/drivers/dma/xilinx/xilinx_dma.c
[2]: https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/xilinx/xilinx_axienet_main.c#L238 
[3]: http://lkml.iu.edu/hypermail/linux/kernel/1804.0/00367.html 

This series is based on dmaengine tree commit: #a38fd8748464

Radhey Shyam Pandey (3):
  dt-bindings: net: xilinx_axienet: convert bindings document to yaml
  dt-bindings: net: xilinx_axienet: Introduce dmaengine binding support
  net: axienet: Introduce dmaengine support

 .../devicetree/bindings/net/xilinx_axienet.txt     |   80 --
 .../devicetree/bindings/net/xilinx_axienet.yaml    |  155 +++
 MAINTAINERS                                        |    1 +
 drivers/net/ethernet/xilinx/xilinx_axienet.h       |  141 +--
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c  | 1050 ++++----------------
 5 files changed, 341 insertions(+), 1086 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/net/xilinx_axienet.txt
 create mode 100644 Documentation/devicetree/bindings/net/xilinx_axienet.yaml

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