Re: [PATCH v16 1/2] dt-bindings: phy: qcom: Add CSI2 C-PHY/DPHY schema

[Bryan O'Donoghue <bod@kernel.org>]

On 03/09/2026 12:53, Vladimir Zapolskiy wrote:
> On 9/1/26 23:15, Bryan O'Donoghue wrote:
>> Add a base schema for the MIPI CSI2 PHYs on Qualcomm SoCs. This PHY
>> supports both DPHY and CPHY operation. A special mode of DPHY operation -
>> called variously split-mode or combo-mode also allows for two sensors to be
>> connected to one PHY.
>>
>> The submitted binding here describes the DPHY modes of operation only. CPHY
>> is left to future work.
> 
> Like I've said in v14 review, the statement above is incorrect, and it has
> to be changed, for whatever reason it hasn't happened so far.
> 
>   From https://lore.kernel.org/all/1e1bc17a-4c7a-4c08-b0c8-2a2ff31fe870@linaro.org/
Well, I'm not trying to describe CPHY here so I'm not claiming it is 
adequately described.

I'll reword this.

>>>> C-PHY bus type is also well described by this version of the bindings.
> 
>> Suggested-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
>> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
>> ---
>>    .../bindings/phy/qcom,x1e80100-csi2-phy.yaml       | 222 +++++++++++++++++++++
>>    1 file changed, 222 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/phy/qcom,x1e80100-csi2-phy.yaml b/Documentation/devicetree/bindings/phy/qcom,x1e80100-csi2-phy.yaml
>> new file mode 100644
>> index 0000000000000..17de0701eb103
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/phy/qcom,x1e80100-csi2-phy.yaml
>> @@ -0,0 +1,222 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/phy/qcom,x1e80100-csi2-phy.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Qualcomm X1E80100 SoC CSI2 PHY
>> +
>> +maintainers:
>> +  - Bryan O'Donoghue <bod@kernel.org>
>> +
>> +description:
>> +  Qualcomm MIPI CSI2 C-PHY/D-PHY combination PHY. Connects MIPI CSI2 sensors
>> +  to Qualcomm's Camera CSI Decoder. The PHY supports both C-PHY and D-PHY
>> +  modes.
>> +
>> +properties:
>> +  compatible:
>> +    const: qcom,x1e80100-csi2-phy
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  clocks:
>> +    maxItems: 3
>> +
>> +  clock-names:
>> +    items:
>> +      - const: core
>> +      - const: timer
>> +      - const: ahb
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  operating-points-v2: true
>> +
>> +  opp-table:
>> +    type: object
>> +
>> +  power-domains:
>> +    items:
>> +      - description: Titan Top GDSC - Titan ISP Block, Global Distributed Switch Controller.
>> +      - description: MMCX voltage rail
>> +      - description: MXC or MXA voltage rail
>> +
>> +  power-domain-names:
>> +    items:
>> +      - const: top
>> +      - const: mmcx
>> +      - const: mx
>> +
>> +  vdda-0p9-supply:
>> +    description: Phandle to a 0.9V regulator supply to a PHY.
>> +
>> +  vdda-1p2-supply:
>> +    description: Phandle to 1.2V regulator supply to a PHY.
>> +
>> +  ports:
>> +    $ref: /schemas/graph.yaml#/properties/ports
>> +
>> +    properties:
>> +      port@0:
>> +        $ref: /schemas/graph.yaml#/$defs/port-base
>> +        description:
>> +          Sensor input. Always present. A single sensor is described by a
>> +          single endpoint with the clock lane at position 0 and one to four
>> +          data lanes.
>> +
>> +          DPHY split mode, where two independent sensors share the same PHY,
>> +          is described by two endpoints, each with its own clock lane position;
>> +          endpoint@0 with clock-lanes = <0> and one or two data-lanes and
>> +          endpoint@1 with clock-lanes = <3> and one data lane.
>> +
>> +        unevaluatedProperties: false
>> +
>> +        patternProperties:
>> +          "^endpoint(@[01])?$":
>> +            $ref: /schemas/media/video-interfaces.yaml#
>> +            unevaluatedProperties: false
>> +            properties:
>> +              bus-type:
>> +                enum:
>> +                  - 1 # MEDIA_BUS_TYPE_CSI2_CPHY
>> +                  - 4 # MEDIA_BUS_TYPE_CSI2_DPHY
>> +
>> +              clock-lanes:
>> +                maxItems: 1
>> +
>> +              data-lanes:
>> +                minItems: 1
>> +                maxItems: 4
>> +                items:
>> +                  minimum: 1
>> +                  maximum: 4
>> +                description:
>> +                  Data lane positions following this endpoint's clock
>> +                  lane. Positions are a per-port logical numbering, not
>> +                  package pad or ball positions.
>> +
>> +            required:
>> +              - bus-type
> 
> A review comment given to v14 is still applicable, 'bus-type' property
> should be set as optional with D-PHY mode fallback.

I believe you said "could" be optional in v14 but, if you actually 
_want_ it optional, I'll update this to reflect, np.

> 
>> +              - data-lanes
>> +              - clock-lanes
> 
> Here 'clock-lanes' is a truly optional proiperty since its value is
> immutable in each endpoint, it should be removed from the list of
> required properties.

Hmm.

I want to make sure clock-lanes is defined and set to the correct value.

For example clock-lanes = <2> for split mode is wrong.
> 
> Also 'clock-lanes' are not expected to be found in C-PHY bus type case.

Right so to both verify the property and not require it from CPHY I will 
make it required only for DPHY.

>> +              - remote-endpoint
>> +
>> +        allOf:
>> +          - if:
>> +              required:
>> +                - endpoint@1
>> +            then:
>> +              properties:
>> +                endpoint@0:
>> +                  properties:
>> +                    clock-lanes:
>> +                      const: 0
>> +                    data-lanes:
>> +                      maxItems: 2
>> +                endpoint@1:
>> +                  properties:
>> +                    clock-lanes:
>> +                      const: 3
>> +                    data-lanes:
>> +                      items:
>> +                        - const: 4
>> +              required:
>> +                - endpoint@0
>> +            else:
>> +              patternProperties:
>> +                "^endpoint(@0)?$":
>> +                  properties:
>> +                    clock-lanes:
>> +                      const: 0
>> +
>> +      port@1:
>> +        $ref: /schemas/graph.yaml#/properties/port
>> +        description: Output to the CAMSS CSID controller.
>> +
>> +    required:
>> +      - port@0
>> +      - port@1
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - clocks
>> +  - clock-names
>> +  - interrupts
>> +  - operating-points-v2
>> +  - power-domains
>> +  - power-domain-names
>> +  - vdda-0p9-supply
>> +  - vdda-1p2-supply
>> +  - ports
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/qcom,x1e80100-camcc.h>
>> +    #include <dt-bindings/clock/qcom,x1e80100-gcc.h>
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +    #include <dt-bindings/media/video-interfaces.h>
>> +    #include <dt-bindings/power/qcom,rpmhpd.h>
>> +
>> +    phy@ace4000 {
>> +        compatible = "qcom,x1e80100-csi2-phy";
>> +        reg = <0x0ace4000 0x2000>;
>> +
>> +        clocks = <&camcc CAM_CC_CSIPHY0_CLK>,
>> +                 <&camcc CAM_CC_CSI0PHYTIMER_CLK>,
>> +                 <&camcc CAM_CC_CORE_AHB_CLK>;
>> +        clock-names = "core",
>> +                      "timer",
>> +                      "ahb";
>> +
>> +        interrupts = <GIC_SPI 477 IRQ_TYPE_EDGE_RISING>;
>> +
>> +        operating-points-v2 = <&csiphy_opp_table>;
>> +
>> +        power-domains = <&camcc CAM_CC_TITAN_TOP_GDSC>,
>> +                        <&rpmhpd RPMHPD_MMCX>,
>> +                        <&rpmhpd RPMHPD_MX>;
>> +        power-domain-names = "top",
>> +                             "mmcx",
>> +                             "mx";
>> +
>> +        vdda-0p9-supply = <&vreg_l2c_0p9>;
>> +        vdda-1p2-supply = <&vreg_l1c_1p2>;
>> +
>> +        ports {
>> +            #address-cells = <1>;
>> +            #size-cells = <0>;
>> +
>> +            port@0 {
>> +                reg = <0>;
>> +                csiphy0_in: endpoint {
>> +                    bus-type = <MEDIA_BUS_TYPE_CSI2_DPHY>;
>> +                    clock-lanes = <0>;
>> +                    data-lanes = <1 2 3 4>;
>> +                    remote-endpoint = <&sensor_out>;
>> +                };
>> +            };
>> +
>> +            port@1 {
>> +                reg = <1>;
>> +                csiphy0_out: endpoint {
>> +                    remote-endpoint = <&csid_in>;
>> +                };
>> +            };
>> +        };
>> +
>> +        csiphy_opp_table: opp-table {
>> +            compatible = "operating-points-v2";
>> +
>> +            opp-300000000 {
>> +                opp-hz = /bits/ 64 <300000000>;
>> +                required-opps = <&rpmhpd_opp_low_svs_d1>,
>> +                                <&rpmhpd_opp_low_svs_d1>;
>> +            };
>> +        };
>> +    };
>>
> 
> Apart of a few minor comments above, everything else looks good to me.
> 
> --
> Best wishes,
> Vladimir