[PATCH RESEND] 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.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
Can we get this merged for v7.2? A matching device tree change was
already merged in v7.2-rc1.


 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