Re: [PATCH V3 4/6] dt-bindings: dma: xlnx,zynqmp-dma: Add Versal Net compatible support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Invalid fallback compatible string `xlnx,zynqmp-dma-1.0` for `amd,versal-net-dma-1.0`.
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--- Patch [4]: [PATCH V3 4/6] dt-bindings: dma: xlnx,zynqmp-dma: Add Versal Net compatible support ---
commit c94f71cbb3b4d274afbe8968d6bb108158803292
Author: Jay Buddhabhatti <jay.buddhabhatti@amd.com>

dt-bindings: dma: xlnx,zynqmp-dma: Add Versal Net compatible support

This commit introduces the amd,versal-net-dma-1.0 compatible string with a
fallback to xlnx,zynqmp-dma-1.0. It also adds a required per-channel reset
property for Versal Gen2 and Versal Net because the DMA channel must be
reset to clear the state left by firmware.

> 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 2da86037ad79e..87c65aef5c7d3 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

[ ... ]

> @@ -18,15 +18,31 @@ maintainers:
>  properties:
>    "#dma-cells":
>      const: 1
>  
>    compatible:
> -    enum:
> -      - amd,versal2-dma-1.0
> -      - xlnx,zynqmp-dma-1.0
> +    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

[Severity: Medium]
Is this fallback compatible string appropriate here?

The commit message explicitly states that a DMA channel reset is essential
because the device is left in a bad state by firmware, and DMA functionality
fails without it. 

If a device tree is parsed by an older OS using the fallback
xlnx,zynqmp-dma-1.0 driver, it will attempt to operate the hardware without
knowing about the new resets property. Since the older driver cannot perform
the required channel reset, won't the DMA functionality fail just as
described?

Should the fallback be removed if the older driver cannot reliably operate
the device?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260810100452.426320-1-nagendra.golla@amd.com?part=4