linux-kernel - Re: [RFC V2 PATCH 2/3] dt-bindings: net: xilinx_axienet: Introduce dmaengine binding support

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Message-ID: <d179f987-6d3b-449f-8f48-4ab0fff43227@linaro.org>
Date:   Wed, 21 Sep 2022 09:45:18 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Sarath Babu Naidu Gaddam <sarath.babu.naidu.gaddam@....com>,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux@...linux.org.uk
Cc:     netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        michal.simek@....com, radhey.shyam.pandey@....com,
        anirudha.sarangi@....com, harini.katakam@....com, git@...inx.com,
        git@....com
Subject: Re: [RFC V2 PATCH 2/3] dt-bindings: net: xilinx_axienet: Introduce
 dmaengine binding support

On 20/09/2022 07:57, Sarath Babu Naidu Gaddam wrote:
> From: Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
> 
> The axiethernet driver will now use dmaengine framework to communicate
> with dma controller IP instead of built-in dma programming sequence.
> 
> To request dma transmit and receive channels the axiethernet driver uses
> generic dmas, dma-names properties. It deprecates axistream-connected
> property, remove axidma reg and interrupt properties from the ethernet
> node. Just to highlight that these DT changes are not backward compatible
> due to major driver restructuring/cleanup done in adopting the dmaengine
> framework.
> 
> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
> Signed-off-by: Sarath Babu Naidu Gaddam <sarath.babu.naidu.gaddam@....com>
> ---
> Changes in V2:
> - None.
> ---
>  .../devicetree/bindings/net/xlnx,axiethernet.yaml  |   39 ++++++++++++--------
>  1 files changed, 23 insertions(+), 16 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/xlnx,axiethernet.yaml b/Documentation/devicetree/bindings/net/xlnx,axiethernet.yaml
> index 780edf3..1dc1719 100644
> --- a/Documentation/devicetree/bindings/net/xlnx,axiethernet.yaml
> +++ b/Documentation/devicetree/bindings/net/xlnx,axiethernet.yaml
> @@ -14,10 +14,8 @@ description: |
>    offloading TX/RX checksum calculation off the processor.
>  
>    Management configuration is done through the AXI interface, while payload is
> -  sent and received through means of an AXI DMA controller. This driver
> -  includes the DMA driver code, so this driver is incompatible with AXI DMA
> -  driver.
> -
> +  sent and received through means of an AXI DMA controller using dmaengine
> +  framework.
>  
>  allOf:
>    - $ref: "ethernet-controller.yaml#"
> @@ -36,19 +34,13 @@ properties:
>  
>    reg:
>      description:
> -      Address and length of the IO space, as well as the address
> -      and length of the AXI DMA controller IO space, unless
> -      axistream-connected is specified, in which case the reg
> -      attribute of the node referenced by it is used.
> -    maxItems: 2
> +      Address and length of the IO space.
> +    maxItems: 1
>  
>    interrupts:
>      description:
> -      Can point to at most 3 interrupts. TX DMA, RX DMA, and optionally Ethernet
> -      core. If axistream-connected is specified, the TX/RX DMA interrupts should
> -      be on that node instead, and only the Ethernet core interrupt is optionally
> -      specified here.
> -    maxItems: 3
> +      Ethernet core interrupt.
> +    maxItems: 1
>  
>    phy-handle: true
>  
> @@ -109,6 +101,7 @@ properties:
>        for the AXI DMA controller used by this device. If this is specified,
>        the DMA-related resources from that device (DMA registers and DMA
>        TX/RX interrupts) rather than this one will be used.
> +    deprecated: true
>  
>    mdio: true
>  
> @@ -118,12 +111,24 @@ properties:
>        and "phy-handle" should point to an external PHY if exists.
>      $ref: /schemas/types.yaml#/definitions/phandle
>  
> +  dmas:
> +    items:
> +      - description: TX DMA Channel phandle and DMA request line number
> +      - description: RX DMA Channel phandle and DMA request line number
> +
> +  dma-names:
> +    items:
> +      - const: tx_chan0
> +      - const: rx_chan0
> +
>  required:
>    - compatible
>    - interrupts
>    - reg
>    - xlnx,rxmem
>    - phy-handle
> +  - dmas
> +  - dma-names
>  
>  additionalProperties: false
>  
> @@ -132,11 +137,13 @@ examples:
>      axi_ethernet_eth: ethernet@...00000 {
>        compatible = "xlnx,axi-ethernet-1.00.a";
>        interrupt-parent = <&microblaze_0_axi_intc>;
> -      interrupts = <2>, <0>, <1>;
> +      interrupts = <1>;

This looks like an ABI break. How do you handle old DTS? Oh wait... you
do not handle it at all.


Best regards,
Krzysztof