Hi Rob,

Thank you for reviewing.
Your comments are helpful as I'm not familiar with the new bindings yet.

On Thu, 6 Feb 2020 17:54:58 +0000 [off-list ref] wrote:

On Thu, Jan 30, 2020 at 02:27:27PM +0900, Kunihiko Hayashi wrote:

quoted

Add devicetree binding documentation for external DMA controller
implemented on Socionext UniPhier SoCs.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
---
 .../bindings/dma/socionext,uniphier-xdmac.yaml     | 57 ++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/socionext,uniphier-xdmac.yaml

diff --git a/Documentation/devicetree/bindings/dma/socionext,uniphier-xdmac.yaml b/Documentation/devicetree/bindings/dma/socionext,uniphier-xdmac.yaml
new file mode 100644
index 00000000..32abf18
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/socionext,uniphier-xdmac.yaml

@@ -0,0 +1,57 @@
+# SPDX-License-Identifier: GPL-2.0

Dual license new bindings:

(GPL-2.0-only OR BSD-2-Clause)

I'll replace with it.

quoted

+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dma/socionext,uniphier-xdmac.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Socionext UniPhier external DMA controller
+
+description: |
+  This describes the devicetree bindings for an external DMA engine to perform
+  memory-to-memory or peripheral-to-memory data transfer capable of supporting
+  16 channels, implemented in Socionext UniPhier SoCs.
+
+maintainers:
+  - Kunihiko Hayashi [off-list ref]
+
+allOf:
+  - $ref: "dma-controller.yaml#"
+
+properties:
+  compatible:
+    items:
+      - const: socionext,uniphier-xdmac

You can drop 'items' for a single item.

I see.
I found some documents didn't have expression for a compatible string.

quoted

+
+  reg:
+    minItems: 1
+    maxItems: 2

You need to say what each entry is:

items:
  - description: ...
  - description: ...

Surely there must be descriotions here.

quoted

+
+  interrupts:
+    maxItems: 1
+
+  "#dma-cells":
+    const: 2
+    description: |
+      DMA request from clients consists of 2 cells:
+        1. Channel index
+        2. Transfer request factor number, If no transfer factor, use 0.
+           The number is SoC-specific, and this should be specified with
+           relation to the device to use the DMA controller.
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - "#dma-cells"

Add:

additionalProperties: false

I'll add it.

quoted

+
+examples:
+  - |
+    xdmac: dma-controller@5fc10000 {
+        compatible = "socionext,uniphier-xdmac";
+        reg = <0x5fc10000 0x1000>, <0x5fc20000 0x800>;
+        interrupts = <0 188 4>;
+        #dma-cells = <2>;
+        dma-channels = <16>;

Not documented. You need at least 'dma-channels: true' to indicate 
you're using this. But you should be able to have some constraints such 
as 'maximum: 16'.

I forgot to document 'dma-channels'. I'll add it.

Thank you,

---
Best Regards,
Kunihiko Hayashi