linux-kernel - Re: [PATCH 1/3] dt-bindings: dma: mediatek,uart-dma: drop mediatek,dma-33bits property

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Message-ID: <20250922204756.GA1294776-robh@kernel.org>
Date: Mon, 22 Sep 2025 15:47:56 -0500
From: Rob Herring <robh@...nel.org>
To: Max Shevchenko <wctrl@...ton.me>
Cc: Sean Wang <sean.wang@...iatek.com>, Vinod Koul <vkoul@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Long Cheng <long.cheng@...iatek.com>, dmaengine@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] dt-bindings: dma: mediatek,uart-dma: drop
 mediatek,dma-33bits property

On Sun, Sep 21, 2025 at 02:03:40PM +0300, Max Shevchenko wrote:
> Many newer SoCs support more than 33 bits for DMA.
> Drop the property in order to switch to the platform data.
> 
> The reference SoCs were taken from the downstream kernel (6.6) for
> the MT6991 SoC.
> 
> Signed-off-by: Max Shevchenko <wctrl@...ton.me>
> ---
>  Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml b/Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml
> index dab468a88942d694525aa391f695c44d192f0c42..9dfdfe81af7edbe3540e4b757547a5d5e6ae810c 100644
> --- a/Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml
> +++ b/Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml
> @@ -22,12 +22,14 @@ properties:
>        - items:
>            - enum:
>                - mediatek,mt2712-uart-dma
> -              - mediatek,mt6795-uart-dma
>                - mediatek,mt8365-uart-dma
>                - mediatek,mt8516-uart-dma
>            - const: mediatek,mt6577-uart-dma
>        - enum:
> -          - mediatek,mt6577-uart-dma
> +          - mediatek,mt6577-uart-dma  # 32 bits
> +          - mediatek,mt6795-uart-dma  # 33 bits

Unless all existing s/w supported mediatek,mt6795-uart-dma, you just 
broke this platform which was relying on the fallback compatible. 

> +          - mediatek,mt6779-uart-dma  # 34 bits
> +          - mediatek,mt6985-uart-dma  # 35 bits
>  
>    reg:
>      minItems: 1
> @@ -56,10 +58,6 @@ properties:
>        Number of virtual channels of the UART APDMA controller
>      maximum: 16
>  
> -  mediatek,dma-33bits:
> -    type: boolean
> -    description: Enable 33-bits UART APDMA support

If this is in use, you need to mark it 'deprecated' instead.

> -
>  required:
>    - compatible
>    - reg
> @@ -116,7 +114,6 @@ examples:
>              dma-requests = <12>;
>              clocks = <&pericfg CLK_PERI_AP_DMA>;
>              clock-names = "apdma";
> -            mediatek,dma-33bits;
>              #dma-cells = <1>;
>          };
>      };
> 
> -- 
> 2.51.0
>