Re: [PATCH v2 6/7] dt-bindings: media: Add i.MX8 ISI DT bindings

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 12/07/2022 12:25, Laurent Pinchart wrote:
> Hi Krzysztof,
> 
> On Tue, Jul 12, 2022 at 09:49:45AM +0200, Krzysztof Kozlowski wrote:
>> On 12/07/2022 02:02, Laurent Pinchart wrote:
>>> The Image Sensing Interface (ISI) combines image processing pipelines
>>> with DMA engines to process and capture frames originating from a
>>> variety of sources. The inputs to the ISI go through Pixel Link
>>> interfaces, and their number and nature is SoC-dependent. They cover
>>> both capture interfaces (MIPI CSI-2 RX, HDMI RX) and memory inputs.
>>>
>>> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>>> ---
>>> Changes since v1:
>>>
>>> - Fix compatible string checks in conditional schema
>>> - Fix interrupts property handling
>>> ---
>>>  .../bindings/media/nxp,imx8-isi.yaml          | 148 ++++++++++++++++++
>>>  1 file changed, 148 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/media/nxp,imx8-isi.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/media/nxp,imx8-isi.yaml b/Documentation/devicetree/bindings/media/nxp,imx8-isi.yaml
>>> new file mode 100644
>>> index 000000000000..390dfa03026b
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/media/nxp,imx8-isi.yaml
>>> @@ -0,0 +1,148 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/media/nxp,imx8-isi.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: i.MX8 Image Sensing Interface
>>> +
>>> +maintainers:
>>> +  - Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>>> +
>>> +description: |
>>> +  The Image Sensing Interface (ISI) combines image processing pipelines with
>>> +  DMA engines to process and capture frames originating from a variety of
>>> +  sources. The inputs to the ISI go through Pixel Link interfaces, and their
>>> +  number and nature is SoC-dependent. They cover both capture interfaces (MIPI
>>> +  CSI-2 RX, HDMI RX, ...) and display engine outputs for writeback support.
>>> +
>>> +properties:
>>> +  compatible:
>>> +    enum:
>>> +      - fsl,imx8mn-isi
>>> +      - fsl,imx8mp-isi
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  clocks:
>>> +    items:
>>> +      - description: The AXI clock
>>> +      - description: The APB clock
>>> +      # TODO: Check if the per-channel ipg_proc_clk clocks need to be specified
>>> +      # as well, in case some SoCs have the ability to control them separately.
>>> +      # This may be the case of the i.MX8[DQ]X(P)
>>> +
>>> +  clock-names:
>>> +    items:
>>> +      - const: axi
>>> +      - const: apb
>>> +
>>> +  fsl,blk-ctrl:
>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>> +    description:
>>> +      A phandle referencing the block control that contains the CSIS to ISI
>>> +      gasket.
>>> +
>>> +  interrupts: true
>>
>> Need generic constraints - min/maxItems.
> 
> I can't set maxItems here, as the value depends on the compatible
> string. It's set below as part of the "allOf". I could set minItems to
> 1, but I don't really see a point in doing so.

Of course you can, just like all other files could.

https://elixir.bootlin.com/linux/v5.19-rc6/source/Documentation/devicetree/bindings/clock/samsung,exynos7-clock.yaml#L57

> 
>>> +
>>> +  power-domains: true
>>
>> Ditto.
> 
> I'll fix this one.
> 
>>> +
>>> +  ports:
>>> +    $ref: /schemas/graph.yaml#/properties/ports
>>> +    description: |
>>> +      Ports represent the Pixel Link inputs to the ISI. Their number and
>>> +      assignment are model-dependent. Each port shall have a single endpoint.
>>> +
>>> +    patternProperties:
>>> +      "^port@[0-9]$":
>>> +        $ref: /schemas/graph.yaml#/properties/port
>>> +        unevaluatedProperties: false
>>> +
>>> +    unevaluatedProperties: false
>>
>> At least one port is always required?
> 
> That's a fair assumption I think. How would you express that ? There's
> no patternRequired as far as I know. Note that the device-dependent
> ports are described in the "allOf" section below, where "required" is
> set per device model.

required:
 - port@0

> 
>>> +
>>> +required:
>>> +  - compatible
>>> +  - reg
>>> +  - interrupts
>>> +  - clocks
>>> +  - clock-names
>>> +  - fsl,blk-ctrl
>>> +  - ports
>>> +
>>> +allOf:
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            const: fsl,imx8mn-isi
>>> +    then:
>>> +      properties:
>>> +        interrupts:
>>> +          maxItems: 1
>>> +        ports:
>>> +          properties:
>>> +            port@0:
>>> +              description: MIPI CSI-2 RX
>>> +          required:
>>> +            - port@0
>>> +
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            const: fsl,imx8mp-isi
>>> +    then:
>>> +      properties:
>>> +        interrupts:
>>> +          maxItems: 2
>>
>> You need to describe the items.
> 
> It's one interrupt per pipeline. Can I add the description to the
> generic interrupts property instead of documenting each item
> individually ? Something along the lines of
> 
>   interrupts:
>     description: Processing pipeline interrupts, one per pipeline
> 

This sounds good, thanks!


Best regards,
Krzysztof