Re: [PATCH RESEND] dt-bindings: PCI: mediatek-gen3: Allow memory-region for restricted DMA buffer

On Mon, Jul 20, 2026 at 05:21:15PM +0800, Chen-Yu Tsai wrote:
> On some SoCs without an IOMMU behind the PCIe controller, the PCIe
> controller memory access could be limited to a small region by the
> firmware configuring a memory protection unit. This memory region
> must be assigned to the PCIe controller so that the OS knows to
> use that region. Otherwise PCIe devices would not work properly.
> 
> Allow the memory-region property with one item pointing to a
> restricted DMA buffer.
> 
> Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
> Acked-by: Rob Herring (Arm) <[email protected]>
> Signed-off-by: Chen-Yu Tsai <[email protected]>
> ---
> Can we get this merged for v7.2? A matching device tree change was
> already merged in v7.2-rc1.
> 

This is not a bug fix, so not sure if this patch can be applied for 7.2. But DTS
change getting applied before the binding change was a mistake first of all.

- Mani

> 
>  Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml b/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml
> index fbc0378392d4..b88717dec1fa 100644
> --- a/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml
> +++ b/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml
> @@ -116,6 +116,10 @@ properties:
>    power-domains:
>      maxItems: 1
>  
> +  memory-region:
> +    maxItems: 1
> +    description: phandle to restricted DMA buffer
> +
>    mediatek,pbus-csr:
>      $ref: /schemas/types.yaml#/definitions/phandle-array
>      items:
> -- 
> 2.55.0.229.g6434b31f56-goog
> 

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