1. There are 2 mmsys, namely vdosys0 and vdosys1 in mt8195.
   Each of them is bound to a display pipeline, so add their
   definition in mtk-mmsys documentation with 2 compatibles.

2. Add description for power-domain property.

Signed-off-by: jason-jh.lin <redacted>
---
this patch is base on [1][2]

[1] dt-bindings: arm: mediatek: mmsys: convert to YAML format
- https://patchwork.kernel.org/project/linux-mediatek/patch/20210519161847.3747352-1-fparent@baylibre.com/
[2] dt-bindings: arm: mediatek: mmsys: add MT8365 SoC binding
- https://patchwork.kernel.org/project/linux-mediatek/patch/20210519161847.3747352-2-fparent@baylibre.com/
---
 .../devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml  | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml
index 2d4ff0ce387b..68cb330d7595 100644
--- a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml
+++ b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml

@@ -30,6 +30,8 @@ properties:
               - mediatek,mt8173-mmsys
               - mediatek,mt8183-mmsys
               - mediatek,mt8365-mmsys
+              - mediatek,mt8195-vdosys0
+              - mediatek,mt8195-vdosys1
           - const: syscon
       - items:
           - const: mediatek,mt7623-mmsys

@@ -39,6 +41,12 @@ properties:
   reg:
     maxItems: 1

+  power-domains:
+    description:
+      A phandle and PM domain specifier as defined by bindings
+      of the power controller specified by phandle. See
+      Documentation/devicetree/bindings/power/power-domain.yaml for details.
+