The mt8192 iommu support 0~16GB iova. We separate it to four banks:
0~4G; 4G~8G; 8G~12G; 12G~16G.

The "dma-ranges" could be used to adjust the bank we locate.
If we don't set this property. The default range always is 0~4G.

Here we don't have actual bus/parent concept here.  And the iova
requirement is for our HW. Thus put the property in our node.

Signed-off-by: Irui Wang <redacted>
---
 Documentation/devicetree/bindings/media/mediatek-vcodec.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/media/mediatek-vcodec.txt b/Documentation/devicetree/bindings/media/mediatek-vcodec.txt
index 06db6837cefd..b7801e3c354a 100644
--- a/Documentation/devicetree/bindings/media/mediatek-vcodec.txt
+++ b/Documentation/devicetree/bindings/media/mediatek-vcodec.txt

@@ -22,6 +22,8 @@ Required properties:
 - iommus : should point to the respective IOMMU block with master port as
   argument, see Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml
   for details.
+- dma-ranges : describes how the physical address space of the IOMMU maps
+  to memory.
 One of the two following nodes:
 - mediatek,vpu : the node of the video processor unit, if using VPU.
 - mediatek,scp : the node of the SCP unit, if using SCP.

-- 
2.18.0
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