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

[Chen-Yu Tsai <wenst@chromium.org>]

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.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
This patch compliments another patch that moved the memory-region from
the PCIe device to the PCIe controller [1].

[1] https://lore.kernel.org/all/20260430120725.241779-1-wenst@chromium.org/

 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 4db700fc36ba..4a9e41d01628 100644
--- a/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml
+++ b/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml
@@ -115,6 +115,10 @@ 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:
-- 
2.54.0.563.g4f69b47b94-goog