RE: [PATCH v12 2/8] dt-bindings: media: platform: visconti: Add Toshiba Visconti Video Input Interface

Hello Laurent.

Thank you for your review comments.

-----Original Message-----
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Sent: Thursday, January 2, 2025 6:56 PM
To: ishikawa yuji(石川 悠司 ○ＲＤＣ□ＡＩＴＣ○ＥＡ開)
[off-list ref]
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>; Rob Herring
[off-list ref]; Krzysztof Kozlowski [off-list ref]; Conor Dooley
[off-list ref]; Sakari Ailus [off-list ref]; Hans
Verkuil [off-list ref]; iwamatsu nobuhiro(岩松 信洋 ○ＤＩＴＣ
□ＤＩＴ○ＯＳＴ) [off-list ref];
linux-media@vger.kernel.org; linux-kernel@vger.kernel.org;
linux-arm-kernel@lists.infradead.org; devicetree@vger.kernel.org
Subject: Re: [PATCH v12 2/8] dt-bindings: media: platform: visconti: Add
Toshiba Visconti Video Input Interface

Hi Ishikawa-san,

Thank you for the patch.

On Mon, Nov 25, 2024 at 06:21:40PM +0900, Yuji Ishikawa wrote:

quoted

Adds the Device Tree binding documentation that allows to describe the
Video Input Interface found in Toshiba Visconti SoCs.

Signed-off-by: Yuji Ishikawa <redacted>
Reviewed-by: Nobuhiro Iwamatsu <redacted>
---
Changelog v2:
- no change

Changelog v3:
- no change

Changelog v4:
- fix style problems at the v3 patch
- remove "index" member
- update example

Changelog v5:
- no change

Changelog v6:
- add register definition of BUS-IF and MPU

Changelog v7:
- remove trailing "bindings" from commit header message
- remove trailing "Device Tree Bindings" from title
- fix text wrapping of description
- change compatible to visconti5-viif
- explicitly define allowed properties for port::endpoint

Changelog v8:
- Suggestion from Krzysztof Kozlowski
  - rename bindings description file
  - use block style array instead of inline style
  - remove clock-lane (as it is fixed at position 0)
  - update sample node's name
  - use lowercase hex for literals
- Suggestion from Laurent Pinchart
  - update description message port::description
  - remove port::endpoint::bus-type as it is fixed to <4>
  - remove port::endpoint::clock-lanes from example
  - add port::endpoint::data-lanes to required parameters list
  - fix sequence of data-lanes: <1 2 3 4> because current driver does not

support data reordering

quoted

  - update port::endpoint::data-lanes::description
  - remove redundant type definition for port::endpoint::data-lanes

Changelog v9:
- place "required" after "properties"
- dictionary ordering of properties

Changelog v10:
- no change

Changelog v11:
- no change

Changelog v12:
- remove property "clock-noncontinuous" as VIIF switches both modes
automatically
- remove property "link-frequencies" as VIIF does not use the
information
- remove reg[2] and interrupts[3] which are used for CSI2RX driver
- update example to refer csi2rx for remote-endpoint

 .../media/toshiba,visconti5-viif.yaml         | 95

+++++++++++++++++++

quoted

 1 file changed, 95 insertions(+)
 create mode 100644
Documentation/devicetree/bindings/media/toshiba,visconti5-viif.yaml

diff --git
a/Documentation/devicetree/bindings/media/toshiba,visconti5-viif.yaml
b/Documentation/devicetree/bindings/media/toshiba,visconti5-viif.yaml
new file mode 100644
index 000000000000..ef0452a47e98

--- /dev/null
+++ b/Documentation/devicetree/bindings/media/toshiba,visconti5-viif.y
+++ aml

@@ -0,0 +1,95 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML 1.2
+---
+$id: http://devicetree.org/schemas/media/toshiba,visconti5-viif.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Toshiba Visconti5 SoC Video Input Interface
+
+maintainers:
+  - Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
+
+description: |-
+  Toshiba Visconti5 SoC Video Input Interface (VIIF) receives
+videostream
+  from MIPI CSI-2 receiver device, processes the stream with image
+signal
+  processors (L1ISP, L2ISP), then stores pictures to main memory.
+
+properties:
+  compatible:
+    const: toshiba,visconti5-viif
+
+  reg:
+    items:
+      - description: Registers for capture control
+      - description: Registers for bus interface unit control
+      - description: Registers for Memory Protection Unit

I'm a bit surprised by the lack of clocks.

The VIIF HW requires clock input. However, since the clock controller driver is still in development and no corresponding clock source is available,
I did not describe the VIIF clock in the device tree and the binding.
I understand that a clock should be defined in the binding.
For the next patch, I'll add a clock definition to the binding.

quoted

+
+  interrupts:
+    items:
+      - description: Sync Interrupt
+      - description: Status (Error) Interrupt
+      - description: L1ISP Interrupt
+
+  port:
+    $ref: /schemas/graph.yaml#/$defs/port-base
+    unevaluatedProperties: false
+    description: CSI-2 input port, with a single endpoint connected to the

CSI-2 transmitter.

quoted

+
+    properties:
+      endpoint:
+        $ref: video-interfaces.yaml#
+        additionalProperties: false
+
+        properties:
+          data-lanes:
+            description: VIIF supports 1, 2, 3 or 4 data lanes
+            minItems: 1
+            items:
+              - const: 1
+              - const: 2
+              - const: 3
+              - const: 4

Now that the CSI-2 receiver is modeled as a separate DT node, I don't think
data-lanes is applicable anymore. The interface between the CSI-2 receiver
and the VIIF isn't a CSI-2 bus.

I think you can simplify the bindings by switching from port-base to port, as you
don't need to specify additional properties for the
endpoint:

  port:
    $ref: /schemas/graph.yaml#/$defs/port
    description:
      CSI-2 input port, with a single endpoint connected to the CSI-2
      transmitter.

Please test this though (by running the DT bindings checks).

I'll remove CSI-2 specific descriptions.
Also I'll use a reference to port.

quoted

+
+          remote-endpoint: true
+
+        required:
+          - data-lanes
+          - remote-endpoint
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - port
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        video@1c000000 {
+            compatible = "toshiba,visconti5-viif";
+            reg = <0 0x1c000000 0 0x6000>,
+                  <0 0x1c00e000 0 0x1000>,
+                  <0 0x2417a000 0 0x1000>;
+            interrupts = <GIC_SPI 64 IRQ_TYPE_LEVEL_HIGH>,
+                         <GIC_SPI 67 IRQ_TYPE_LEVEL_HIGH>,
+                         <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>;
+
+            port {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                csi_in0: endpoint {
+                    data-lanes = <1 2>;
+                    remote-endpoint = <&csi2rx_out0>;
+                };
+            };
+        };
+    };

--
Regards,

Laurent Pinchart

Regards,
Yuji Ishikawa