Re: [PATCH net-next v10 1/6] dt-bindings: net: pcs: add rockchip,rk3568-xpcs support

[Coia Prant <coiaprant@gmail.com>]

On October 6, 2026 9:24:28 PM GMT+08:00, Rob Herring <robh@kernel.org> wrote:
>On Tue, Oct 06, 2026 at 06:30:03AM +0800, Coia Prant wrote:
>> Add device tree binding documentation for the Synopsys DesignWare
>> XPCS integrated on the Rockchip RK3568 SoC.
>> 
>> The XPCS is accessed over the APB3 bus and internally connected to
>> a Naneng Combo SerDes PHY.  It supports 1000BASE-X, SGMII, and
>> QSGMII modes, with four MII ports.
>> 
>> The four MII ports are described as ethernet-pcs-mii@N child nodes,
>> consumed by the Rockchip XPCS glue driver later in this series.
>> 
>> phys and phy-names are required because dtbs_check only validates
>> required properties for enabled nodes. The SerDes link is a board-level
>> design choice (combphy1 on some boards, combphy2 on others), so these
>> properties must be provided by the board device tree, not the SoC dtsi.
>> 
>> The CRU reset lines (SRST_XPCS*) are intentionally not described: no
>> in-tree user requests them, and bring-up relies on the PD_PIPE power
>> domain, the SerDes PHY and the in-IP soft reset. They can be added
>> later as optional without breaking ABI.
>> 
>> Signed-off-by: Coia Prant <coiaprant@gmail.com>
>> ---
>>  .../net/pcs/rockchip,rk3568-xpcs.yaml         | 110 ++++++++++++++++++
>>  1 file changed, 110 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/net/pcs/rockchip,rk3568-xpcs.yaml
>> 
>> diff --git a/Documentation/devicetree/bindings/net/pcs/rockchip,rk3568-xpcs.yaml b/Documentation/devicetree/bindings/net/pcs/rockchip,rk3568-xpcs.yaml
>> new file mode 100644
>> index 0000000000000..703fcff0e3f70
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/pcs/rockchip,rk3568-xpcs.yaml
>> @@ -0,0 +1,110 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/net/pcs/rockchip,rk3568-xpcs.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Rockchip RK3568 Synopsys DesignWare Ethernet PCS
>> +
>> +maintainers:
>> +  - Coia Prant <coiaprant@gmail.com>
>> +
>> +description: |
>> +  Rockchip RK3568 SoC integrates a Synopsys DesignWare Ethernet Physical
>> +  Coding Sublayer (XPCS).
>> +  The PCS provides an interface between the Media Access Control (MAC)
>> +  and the Physical Medium Attachment (PMA) sublayer through a Media
>> +  Independent Interface (GMII).
>> +
>> +  The XPCS is accessed over the APB3 bus and internally connected to a
>> +  Naneng Combo SerDes PHY.
>> +  It supports 1000BASE-X, SGMII and QSGMII modes.
>> +
>> +  The block contains four MII ports that can be individually enabled and
>> +  routed to one of the Ethernet GMAC controllers via the pcs-handle
>> +  property in the MAC device tree node.
>> +
>> +properties:
>> +  compatible:
>> +    const: rockchip,rk3568-xpcs
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  "#address-cells":
>> +    const: 1
>> +
>> +  "#size-cells":
>> +    const: 0
>> +
>> +  clocks:
>> +    items:
>> +      - description: APB3 bus interface clock (clk_csr_i), required for register access
>> +      - description: EEE clock (clk_eee_i), required for Energy Efficient Ethernet operation
>> +
>> +  clock-names:
>> +    items:
>> +      - const: csr
>> +      - const: eee
>> +
>> +  phys:
>> +    maxItems: 1
>> +
>> +  phy-names:
>> +    const: serdes
>
>You don't really need phy-names if there is only 1 entry.
>
>> +
>> +  power-domains:
>> +    maxItems: 1
>> +
>> +patternProperties:
>> +  "^ethernet-pcs-mii@[0-3]$":
>> +    type: object
>> +    description:
>> +      One of the four MII ports of the XPCS. The port is linked to an
>> +      Ethernet MAC controller via the pcs-handle property in the MAC's
>> +      device tree node.
>> +
>> +    properties:
>> +      reg:
>> +        description: MII port number.
>> +        enum: [0, 1, 2, 3]
>> +
>> +    required:
>> +      - reg
>
>Why the child nodes? They don't contain anything.
>
>Perhaps that's due to pcs-handle not supporting arg cells to pass the 
>port number? That's about to change[1].
>
>Rob
>
>[1] https://github.com/devicetree-org/dt-schema/pull/198

Hi Rob,

Both points make sense.

1. I'll drop phy-names since there's only a single entry.

2. For the ethernet-pcs-mii child nodes: you're right that they only
   contain 'reg'. The reason I used child nodes is because pcs-handle
   arg cells are not available yet -- PR #198 is still open and in
   RFC/change-request state.

   The RZN1 MII converter binding does the same thing: it declares
   MII ports as subnodes and references the PCS via pcs-handle, until
   arg cells land.

   So I'd like to keep the child nodes as a temporary workaround, and
   I'll add a note in the binding that this can be simplified once
   PR #198 is merged.

Thanks,
Coia