Re: [PATCH v4 4/6] dt-bindings: dma: xlnx,zynqmp-dma: Add Versal Net compatible support

[Conor Dooley <conor@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 4128 bytes --]

On Fri, Oct 09, 2026 at 09:30:13AM +0530, Golla Nagendra wrote:
> From: Jay Buddhabhatti <jay.buddhabhatti@amd.com>
> 
> Introduce a new compatible string amd,versal-net-dma-1.0 for Versal Net
> ZDMA. The new compatible requires xlnx,zynqmp-dma-1.0 as a fallback.
> 
> Add a reset property to describe the per-channel reset line exposed
> on Versal Gen2 and Versal Net. Mark the resets property as required
> for both Versal Gen2 and Versal Net, and not applicable for other
> platforms.
> 
> Note that making resets required for Versal Gen2 and Versal Net results
> in an ABI break, but this is unavoidable. While the driver works in many
> scenarios when no other firmware has used the DMA prior to Linux boot,
> there is no guarantee the channel is left in a clean state. In observed
> error scenarios, a reset is necessary before Linux can reconfigure the IP
> after previous use by other firmware components. Due to configuration
> differences or the DMA being left in a bad state, DMA functionality fails
> when sequential software components use the channel (e.g., firmware before
> Linux boot). The channel can only be cleanly re-configured after a
> per-channel reset, making it essential. This ABI break is only applied
> to Versal Gen2 and Versal Net where the per-channel reset capability is
> available.
> 
> Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@amd.com>
> Co-developed-by: Golla Nagendra <nagendra.golla@amd.com>
> Signed-off-by: Golla Nagendra <nagendra.golla@amd.com>
> ---
>  .../bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml   | 34 +++++++++++++++++-----
>  1 file changed, 27 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml b/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
> index 2da86037ad79..ff8c9a0e5559 100644
> --- a/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
> +++ b/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
> @@ -16,17 +16,17 @@ maintainers:
>    - Harini Katakam <harini.katakam@amd.com>
>    - Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
>  
> -allOf:
> -  - $ref: ../dma-controller.yaml#
> -
>  properties:
>    "#dma-cells":
>      const: 1
>  
>    compatible:
> -    enum:
> -      - amd,versal2-dma-1.0
> -      - xlnx,zynqmp-dma-1.0

This used to be an enum, so please preserve it as one.

> +    oneOf:
> +      - const: amd,versal2-dma-1.0
> +      - const: xlnx,zynqmp-dma-1.0
> +      - items:
> +          - const: amd,versal-net-dma-1.0
> +          - const: xlnx,zynqmp-dma-1.0
>  
>    reg:
>      description: memory map for gdma/adma module access
> @@ -59,6 +59,9 @@ properties:
>    power-domains:
>      maxItems: 1
>  
> +  resets:
> +    maxItems: 1
> +
>    dma-coherent: true
>  
>  required:
> @@ -70,13 +73,29 @@ required:
>    - clock-names
>    - xlnx,bus-width
>  
> +allOf:
> +  - $ref: ../dma-controller.yaml#
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - amd,versal2-dma-1.0
> +              - amd,versal-net-dma-1.0
> +    then:
> +      required:
> +        - resets

The change here for versal2 is an ABI break (new required property) and
needs to be split out into a standalone patch. The new support can go on
top.
pw-bot: changes-requested

Thanks,
Conor.

> +    else:
> +      properties:
> +        resets: false
> +
>  additionalProperties: false
>  
>  examples:
>    - |
>  
>      fpd_dma_chan1: dma-controller@fd500000 {
> -      compatible = "xlnx,zynqmp-dma-1.0";
> +      compatible = "amd,versal-net-dma-1.0", "xlnx,zynqmp-dma-1.0";
>        reg = <0xfd500000 0x1000>;
>        interrupt-parent = <&gic>;
>        interrupts = <0 117 0x4>;
> @@ -84,5 +103,6 @@ examples:
>        clock-names = "clk_main", "clk_apb";
>        clocks = <&zynqmp_clk 19>, <&zynqmp_clk 31>;
>        xlnx,bus-width = <128>;
> +      resets = <&reset 0>;
>        dma-coherent;
>      };
> 
> -- 
> 2.43.7
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]