Re: [PATCH v2 2/7] arm64: dts: mediatek: mt8173: Add and use UART AP_DMA controller

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The newly added `apdma` node uses a `reg` base address that overlaps exactly with the DMA channel already assigned to `i2c4` (`0x11000300`), leading to guaranteed probe failures for one of the devices.
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--- Patch [2]: [PATCH v2 2/7] arm64: dts: mediatek: mt8173: Add and use UART AP_DMA controller ---
commit 02e7bfa1531235c71580128c63236a6715a1e297
Author: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

arm64: dts: mediatek: mt8173: Add and use UART AP_DMA controller

This commit adds the UART AP_DMA controller to the MT8173 device tree and
assigns its DMA channels to the four UART controllers. This is intended to
increase data TX/RX efficiency for the UARTs.

> diff --git a/arch/arm64/boot/dts/mediatek/mt8173.dtsi b/arch/arm64/boot/dts/mediatek/mt8173.dtsi
> index 78c2ccd5be132..7297225f61c99 100644
> --- a/arch/arm64/boot/dts/mediatek/mt8173.dtsi
> +++ b/arch/arm64/boot/dts/mediatek/mt8173.dtsi
> @@ -673,6 +673,25 @@ gic: interrupt-controller@10221000 {
>  				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_HIGH)>;
>  		};
>  
> +		apdma: dma-controller@11000300 {
> +			compatible = "mediatek,mt8173-uart-dma", "mediatek,mt6577-uart-dma";
> +			reg = <0 0x11000300 0 0x80>, <0 0x11000380 0 0x80>,

[Severity: High]
Does this node's first reg region conflict with the DMA region already
assigned to the i2c4 controller?

Looking at the existing i2c4 node later in the same file:

		i2c4: i2c@11011000 {
			compatible = "mediatek,mt8173-i2c";
			reg = <0 0x11011000 0 0x70>,
			      <0 0x11000300 0 0x80>;

Since both devices claim 0x11000300 and apdma is not marked as disabled,
would request_mem_region() return -EBUSY and fail to probe one of the
devices? This could break i2c4-attached devices like trackpads on
mt8173-elm boards.

> +			      <0 0x11000400 0 0x80>, <0 0x11000480 0 0x80>,
> +			      <0 0x11000500 0 0x80>, <0 0x11000580 0 0x80>,
> +			      <0 0x11000600 0 0x80>, <0 0x11000680 0 0x80>;

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260707154841.198870-1-angelogioacchino.delregno@collabora.com?part=2