[PATCH v2 7/8] dt-bindings: display: allwinner: Split H616 DE33 layer reg space

[Jernej Skrabec <jernej.skrabec@gmail.com>]

From: Jernej Skrabec <jernej.skrabec@gmail.com>

As it turns out, current H616 DE33 binding was written based on
incomplete understanding of DE33 design. Namely, planes are shared
resource and not tied to specific mixer, which was the case for previous
generations of Display Engine (DE3 and earlier).

This means that current DE33 binding doesn't properly reflect HW and
using it would mean that second mixer (used for second display output)
can't be supported.

Remove layer register space, which will be represented with additional
node, and replace it with phandle, which will point to that new, shared
node. That way, all mixers can share same layers.

There is no user of this binding yet, so changes can be made safely,
without breaking any backward compatibility.

Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
---
Changes in v1:
- update commit subject
- reword commit message

 .../display/allwinner,sun8i-a83t-de2-mixer.yaml  | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/allwinner,sun8i-a83t-de2-mixer.yaml b/Documentation/devicetree/bindings/display/allwinner,sun8i-a83t-de2-mixer.yaml
index cbd18fd83e52..064e4ca7e419 100644
--- a/Documentation/devicetree/bindings/display/allwinner,sun8i-a83t-de2-mixer.yaml
+++ b/Documentation/devicetree/bindings/display/allwinner,sun8i-a83t-de2-mixer.yaml
@@ -46,6 +46,10 @@ properties:
   resets:
     maxItems: 1
 
+  allwinner,planes:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: Phandle of Display Engine 3.3 planes node
+
   ports:
     $ref: /schemas/graph.yaml#/properties/ports
 
@@ -74,22 +78,22 @@ allOf:
       properties:
         reg:
           description: |
-            Registers for controlling individual layers of the display
-            engine (layers), global control (top), and display blending
-            control (display). Names are from Allwinner BSP kernel.
-          maxItems: 3
+            Registers for display blending control (display) and global
+            control (top). Names are from Allwinner BSP kernel.
+          maxItems: 2
         reg-names:
           items:
-            - const: layers
-            - const: top
             - const: display
+            - const: top
       required:
         - reg-names
+        - allwinner,planes
 
     else:
       properties:
         reg:
           maxItems: 1
+        allwinner,planes: false
 
 required:
   - compatible
-- 
2.54.0