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

[Manivannan Sadhasivam]

On Fri, May 08, 2026 at 02:36:32PM +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.
> 

So this means, the PCIe devices can only access a specific carveout memory
configured by MPU for DMA? If so, you should use 'dma-ranges' as suggested by
Rob.

'memory-region' also serves the purpose, but for PCI, we have the dedicated
'dma-ranges' property.

- Mani

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