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[60.250.196.139]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-369514361b6sm15491821a91.12.2026.05.19.20.06.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 May 2026 20:06:11 -0700 (PDT) Message-ID: Date: Wed, 20 May 2026 11:06:05 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/4] dt-bindings: display: verisilicon, dc: generalize for single-output variants To: Conor Dooley , Icenowy Zheng Cc: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, ychuang3@nuvoton.com, schung@nuvoton.com, yclu4@nuvoton.com, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260519055114.1886525-1-a0987203069@gmail.com> <20260519055114.1886525-2-a0987203069@gmail.com> <20260519-fretful-blush-1aac18fa1360@spud> Content-Language: en-US From: Joey Lu In-Reply-To: <20260519-fretful-blush-1aac18fa1360@spud> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 5/20/2026 12:47 AM, Conor Dooley wrote: > On Tue, May 19, 2026 at 03:26:58PM +0800, Icenowy Zheng wrote: >> 在 2026-05-19二的 13:51 +0800，Joey Lu写道： >>> The existing schema assumes a fixed clock/reset topology and dual- >>> output >>> port structure matching the DC8200 IP block.  This prevents reuse for >>> single-output variants such as the Verisilicon DCU Lite used in the >>> Nuvoton MA35D1 SoC. >>> >>> Rework the schema so that variant-specific constraints are expressed >>> via allOf/if-then-else: >>> >>> - The thead,th1520-dc8200 compatible keeps its existing five-clock, >>>   three-reset, dual-port requirements. >>> >>> - A standalone verisilicon,dc compatible covers IPs whose identity is >>>   discovered entirely through hardware registers; these have flexible >>>   clock and reset counts, a single 'port' property, and no 'ports' >>>   requirement. >>> >>> Changes to the base schema: >>> - Replace the fixed clock/reset items lists with minItems/maxItems >>>   ranges; variant sub-schemas tighten the constraints via if-then- >>> else. >>> - Add a 'port' property (graph.yaml single-port alias) alongside the >>>   existing 'ports', for single-output variants. >>> - Drop the unconditional 'ports' requirement; each if-branch enforces >>>   its own port topology. >>> - Tighten additionalProperties to unevaluatedProperties to allow >>>   per-variant schemas to add their own constraints cleanly. >>> - Fix a stray space in the port@0 description. >>> - Add a DT example for the generic verisilicon,dc compatible >>>   (Nuvoton MA35D1 DCU Lite). >>> >>> Signed-off-by: Joey Lu >>> --- >>>  .../bindings/display/verisilicon,dc.yaml      | 135 ++++++++++++++-- >>> -- >>>  1 file changed, 108 insertions(+), 27 deletions(-) >>> >>> diff --git >>> a/Documentation/devicetree/bindings/display/verisilicon,dc.yaml >>> b/Documentation/devicetree/bindings/display/verisilicon,dc.yaml >>> index 9dc35ab973f2..3a814c2e083e 100644 >>> --- a/Documentation/devicetree/bindings/display/verisilicon,dc.yaml >>> +++ b/Documentation/devicetree/bindings/display/verisilicon,dc.yaml >>> @@ -14,10 +14,12 @@ properties: >>>      pattern: "^display@[0-9a-f]+$" >>> >>>    compatible: >>> -    items: >>> -      - enum: >>> -          - thead,th1520-dc8200 >> You should add a fallback compatible here for your SoC, in case its >> integration gets something quirky; this compatible is usually not >> consumed by the driver (see how thead,th1520-dc8200 exists in the >> binding but not the driver). > s/fallback compatible/soc-specific compatible/, but yes. > NAK to what's been done here, especially after the discussions on > earlier versions of this verisilicon binding. > pw-bot: changes-requested Understood. I will add `nuvoton,ma35d1-dcu` as the SoC-specific compatible string paired with `verisilicon,dc` as the generic fallback, matching the pattern used for `thead,th1520-dc8200`. The standalone `verisilicon,dc` compatible will be removed from the binding. The driver match table is not changed since hardware detection is done via ID registers. >>> -      - const: verisilicon,dc # DC IPs have discoverable ID/revision >>> registers >>> +    oneOf: >>> +      - items: >>> +          - enum: >>> +              - thead,th1520-dc8200 >>> +          - const: verisilicon,dc >>> +      - const: verisilicon,dc  # DC IPs have discoverable >>> ID/revision registers >>> >>>    reg: >>>      maxItems: 1 >>> @@ -26,32 +28,24 @@ properties: >>>      maxItems: 1 >>> >>>    clocks: >>> -    items: >>> -      - description: DC Core clock >>> -      - description: DMA AXI bus clock >>> -      - description: Configuration AHB bus clock >>> -      - description: Pixel clock of output 0 >>> -      - description: Pixel clock of output 1 >>> +    minItems: 2 >>> +    maxItems: 5 >>> >>>    clock-names: >>> -    items: >>> -      - const: core >>> -      - const: axi >>> -      - const: ahb >>> -      - const: pix0 >>> -      - const: pix1 >>> +    minItems: 2 >>> +    maxItems: 5 >>> >>>    resets: >>> -    items: >>> -      - description: DC Core reset >>> -      - description: DMA AXI bus reset >>> -      - description: Configuration AHB bus reset >>> +    minItems: 1 >>> +    maxItems: 3 >>> >>>    reset-names: >>> -    items: >>> -      - const: core >>> -      - const: axi >>> -      - const: ahb >>> +    minItems: 1 >>> +    maxItems: 3 >>> + >>> +  port: >>> +    $ref: /schemas/graph.yaml#/properties/port >>> +    description: Single video output port for single-output >>> variants. >> Maybe the endpoint numbering rule needs a move to here? (I am not very >> sure). I will add a description to the `port` property noting that endpoint 0 is used for DPI output, which is the only output type for DCUltraLite. >>> >>>    ports: >>>      $ref: /schemas/graph.yaml#/properties/ports >>> @@ -59,7 +53,7 @@ properties: >>>      properties: >>>        port@0: >>>          $ref: /schemas/graph.yaml#/properties/port >>> -        description: The first output channel , endpoint 0 should be >>> +        description: The first output channel, endpoint 0 should be >>>            used for DPI format output and endpoint 1 should be used >>>            for DP format output. >>> >>> @@ -75,9 +69,75 @@ required: >>>    - interrupts >>>    - clocks >>>    - clock-names >>> -  - ports >>> >>> -additionalProperties: false >>> +allOf: >>> +  - if: >>> +      properties: >>> +        compatible: >>> +          contains: >>> +            const: thead,th1520-dc8200 >>> +    then: >>> +      properties: >>> +        clocks: >>> +          items: >>> +            - description: DC Core clock >>> +            - description: DMA AXI bus clock >>> +            - description: Configuration AHB bus clock >>> +            - description: Pixel clock of output 0 >>> +            - description: Pixel clock of output 1 >>> + >>> +        clock-names: >>> +          items: >>> +            - const: core >>> +            - const: axi >>> +            - const: ahb >>> +            - const: pix0 >>> +            - const: pix1 >>> + >>> +        resets: >>> +          items: >>> +            - description: DC Core reset >>> +            - description: DMA AXI bus reset >>> +            - description: Configuration AHB bus reset >>> + >>> +        reset-names: >>> +          items: >>> +            - const: core >>> +            - const: axi >>> +            - const: ahb >>> + >>> +      required: >>> +        - ports >>> + >>> +    else: >>> +      properties: >>> +        clocks: >>> +          items: >>> +            - description: Bus clock that gates register access >>> +            - description: Pixel clock divider for display timing >> Please don't make compatible-specific description strings for >> individual compatibles, and keep these descriptions outside of the if. >> The compatible-specific part should be used to specify what's required >> for the specific SoC, for dt validation purpose. >> >> BTW if the clock is both the working clock and bus clock for the >> controller, I suggest listing it twice, except if the IP core is >> provided without a dedicated core clock (in the case I suggest to use >> "bus" only). > I agree. If the same clock is provided to two+ ports on the IP, that > should still be two+ clocks in the devicetree. > >> Here's an example for "listing it twice": >> ``` >> clocks = <&clk DCU_GATE>, <&clk DCU_GATE>, <&clk DCUP_DIV>; >> clock-names = "core", "bus", "pix0"; >> ``` >> >> Well nonetheless the name "core" does not match the description "Bus >> clock that gates register access". >> >> Thanks, >> Icenowy Understood. I will remove all description strings from the if/else branches; the if/then clauses will only constrain clock-names and reset-names items (name values only, no descriptions). Regarding clock naming: DCU_GATE on MA35D1 is a peripheral gate clock without a separate dedicated core working clock, so I will keep "core" as the name and drop the misleading description "Bus clock that gates register access". The description mismatch was entirely in the if/else strings which are now removed. Thanks. >> >>> + >>> +        clock-names: >>> +          items: >>> +            - const: core >>> +            - const: pix0 >>> + >>> +        resets: >>> +          maxItems: 1 >>> +          description: >>> +            Reset line for the display controller. >>> + >>> +        reset-names: >>> +          items: >>> +            - const: core >>> + >>> +      required: >>> +        - port >>> + >>> +      not: >>> +        required: >>> +          - ports >>> + >>> +unevaluatedProperties: false >>> >>>  examples: >>>    - | >>> @@ -120,3 +180,24 @@ examples: >>>          }; >>>        }; >>>      }; >>> + >>> +  - | >>> +    #include >>> +    #include >>> +    #include >>> + >>> +    display@40260000 { >>> +        compatible = "verisilicon,dc"; >>> +        reg = <0x40260000 0x20000>; >>> +        interrupts = ; >>> +        clocks = <&clk DCU_GATE>, <&clk DCUP_DIV>; >>> +        clock-names = "core", "pix0"; >>> +        resets = <&sys MA35D1_RESET_DISP>; >>> +        reset-names = "core"; >>> + >>> +        port { >>> +            dpi_out: endpoint { >>> +                remote-endpoint = <&panel_in>; >>> +            }; >>> +        }; >>> +    };