linux-kernel - Re: [PATCH v3 2/9] dt-bindings: media: nxp: Add Wave6 video codec device

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Message-ID: <22379203-94f8-468d-a9b6-de67f8fba495@kernel.org>
Date: Fri, 29 Aug 2025 15:57:23 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Nas Chung <nas.chung@...psnmedia.com>, mchehab@...nel.org,
 hverkuil@...all.nl, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de
Cc: linux-media@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-imx@....com,
 linux-arm-kernel@...ts.infradead.org, jackson.lee@...psnmedia.com,
 lafley.kim@...psnmedia.com
Subject: Re: [PATCH v3 2/9] dt-bindings: media: nxp: Add Wave6 video codec
 device

On 29/08/2025 10:46, Nas Chung wrote:
> Add documents for the Wave6 video codec on NXP i.MX SoCs.
Pretty incomplete commit msg. Nothing explaining hardware, nothing
documenting resolution of previous discussions (where is all this
chip&media?).

...


> +
> +properties:
> +  compatible:
> +    enum:
> +      - nxp,imx95-vpu
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  power-domains:
> +    maxItems: 1
> +
> +  memory-region:
> +    maxItems: 1
> +
> +  sram:
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +    description: phandle of the SRAM memory region node.
> +
> +  "#cooling-cells":
> +    const: 2
> +
> +  "#address-cells":
> +    const: 2
> +
> +  "#size-cells":
> +    const: 2
> +
> +  ranges: true
> +
> +patternProperties:
> +  "^video-core@[0-9a-f]+$":
> +    type: object

Missing description.

> +    additionalProperties: false
> +
> +    properties:
> +      compatible:
> +        enum:
> +          - nxp,imx95-vpu-core

Why do you need here compatible? Can this child be anything else? Can it
be re-used? Is it actually a separate block?

Your example suggests that the only distinctive resource are the
interrupt and address space and that's on the edge of calling it a
separate device.

There is some tendency to call such "pseudo-cores" a separate devices in
case of video codec bindings and experience shows these are usually
fake. It's not the same as DP or HDMI sub-block of display pipeline.

That's why you should come here with strong argument what separate piece
of hardware this is.

> +
> +      reg:
> +        maxItems: 1
> +
> +      clocks:
> +        maxItems: 1
> +
> +      power-domains:
> +        maxItems: 1
> +
> +      interrupts:
> +        maxItems: 1
> +
> +    required:
> +      - compatible
> +      - reg
> +      - clocks
> +      - power-domains
> +      - interrupts
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - power-domains
> +  - memory-region
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/clock/nxp,imx95-clock.h>
> +
> +    soc {
> +      #address-cells = <2>;
> +      #size-cells = <2>;
> +
> +      vpu: video-codec@...c0000 {

Unused label, drop

> +        compatible = "nxp,imx95-vpu";
> +        reg = <0x0 0x4c4c0000 0x0 0x10000>;
> +        clocks = <&vpu_blk_ctrl IMX95_CLK_VPUBLK_WAVE>;
> +        power-domains = <&scmi_perf 10>;
> +        memory-region = <&vpu_boot>;
> +        sram = <&sram1>;
> +        #cooling-cells = <2>;
> +        #address-cells = <2>;
> +        #size-cells = <2>;
> +        ranges;
> +
> +        vpucore0: video-core@...80000 {

None of these labels are used, drop.

> +          compatible = "nxp,imx95-vpu-core";
> +          reg = <0x0 0x4c480000 0x0 0x10000>;
> +          clocks = <&scmi_clk 115>;
> +          power-domains = <&scmi_devpd 21>;
> +          interrupts = <GIC_SPI 299 IRQ_TYPE_LEVEL_HIGH>;
> +        };
> +
> +        vpucore1: video-core@...90000 {
> +          compatible = "nxp,imx95-vpu-core";
> +          reg = <0x0 0x4c490000 0x0 0x10000>;
> +          clocks = <&scmi_clk 115>;
> +          power-domains = <&scmi_devpd 21>;
> +          interrupts = <GIC_SPI 300 IRQ_TYPE_LEVEL_HIGH>;
> +        };
> +



Best regards,
Krzysztof