linux-kernel - Re: [PATCH 1/8] dt-bindings: dma: marvell,mmp-dma: Add SpacemiT PDMA compatibility

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Message-ID: <20250611-kabob-unmindful-3b1e9728e77d@spud>
Date: Wed, 11 Jun 2025 17:27:10 +0100
From: Conor Dooley <conor@...nel.org>
To: Guodong Xu <guodong@...cstar.com>
Cc: vkoul@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, dlan@...too.org, paul.walmsley@...ive.com,
	palmer@...belt.com, aou@...s.berkeley.edu, alex@...ti.fr,
	p.zabel@...gutronix.de, drew@...7.com,
	emil.renner.berthing@...onical.com, inochiama@...il.com,
	geert+renesas@...der.be, tglx@...utronix.de,
	hal.feng@...rfivetech.com, joel@....id.au, duje.mihanovic@...le.hr,
	elder@...cstar.com, dmaengine@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev
Subject: Re: [PATCH 1/8] dt-bindings: dma: marvell,mmp-dma: Add SpacemiT PDMA
 compatibility

On Wed, Jun 11, 2025 at 08:57:16PM +0800, Guodong Xu wrote:
> Add "spacemit,pdma-1.0" compatible string to support SpacemiT PDMA
> controller in the Marvell MMP DMA device tree bindings. This enables:
> 
> - Support for SpacemiT PDMA controller configuration
> - New optional properties for platform-specific integration:
>   * clocks: Clock controller for the DMA
>   * resets: Reset controller for the DMA
> 
> Also, add explicit #dma-cells property definition to avoid
> "make dtbs_check W=3" warnings about unevaluated properties.
> 
> The #dma-cells property is defined as 2 cells to maintain compatibility
> with existing ARM device trees. The first cell specifies the DMA request
> line number, while the second cell is currently unused by the driver but
> required for backward compatibility with PXA device tree files.
> 
> Signed-off-by: Guodong Xu <guodong@...cstar.com>
> ---
>  .../bindings/dma/marvell,mmp-dma.yaml           | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/dma/marvell,mmp-dma.yaml b/Documentation/devicetree/bindings/dma/marvell,mmp-dma.yaml
> index d447d5207be0..e117a81414bd 100644
> --- a/Documentation/devicetree/bindings/dma/marvell,mmp-dma.yaml
> +++ b/Documentation/devicetree/bindings/dma/marvell,mmp-dma.yaml
> @@ -18,6 +18,7 @@ properties:
>        - marvell,pdma-1.0
>        - marvell,adma-1.0
>        - marvell,pxa910-squ
> +      - spacemit,pdma-1.0

You need a soc-specific compatible here.

>  
>    reg:
>      maxItems: 1
> @@ -32,6 +33,21 @@ properties:
>        A phandle to the SRAM pool
>      $ref: /schemas/types.yaml#/definitions/phandle
>  
> +  clocks:
> +    description: Clock for the controller
> +    maxItems: 1
> +
> +  resets:
> +    description: Reset controller for the DMA controller
> +    maxItems: 1
> +
> +  '#dma-cells':
> +    const: 2
> +    description:
> +      The first cell contains the DMA request number for the peripheral
> +      device. The second cell is currently unused but must be present for
> +      backward compatibility.

These properties are only valid for your new device, right?
If so, please restrict them to only the spacemit platform.

> +
>    '#dma-channels':
>      deprecated: true
>  
> @@ -52,6 +68,7 @@ allOf:
>            contains:
>              enum:
>                - marvell,pdma-1.0
> +              - spacemit,pdma-1.0
>      then:
>        properties:
>          asram: false
> -- 
> 2.43.0
> 

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