Re: [PATCH v18 3/8] dt-bindings: i3c: Add NXP P3H2x4x i3c-hub support

[Krzysztof Kozlowski <krzk@kernel.org>]

On 03/09/2026 08:21, Lakshay Piplani wrote:
> From: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
> 
> Add bindings for the NXP P3H2x4x (P3H2440/P3H2441/P3H2840/P3H2841)
> multiport I3C hub family. These devices connect to a host via
> I3C/I2C/SMBus and allow communication with multiple downstream
> peripherals.
> 
> Signed-off-by: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
> Signed-off-by: Vikash Bansal <vikash.bansal@nxp.com>
> Signed-off-by: Lakshay Piplani <lakshay.piplani@nxp.com>
> Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> 
> ---
> Changes in v18:
>  - Rebased onto v7.3-rc1; no intended driver behaviour changes
> 
> Changes in v17:
>  - Explain in the binding description that all variants share the same register
>    interface, software reads the target-port count from DEV_CAPAB, and
>    the x0/x1 variants differ only in power-up defaults that the driver
>    overrides
> 
> Changes in v16:
>  - Add an allOf/if-then block for the 4-port variants (nxp,p3h2440 and
>    nxp,p3h2441) that limits i3c@[0-3]/smbus@[0-3] and disallows target
>    ports [4-7], so DTs describing nonexistent ports fail validation
>  - Add #address-cells and #size-cells to the required list, since the hub
>    is a parent bus to the target-port child node
>  - Add an explicit minimum of 0 to the target-port reg constraints, retain
>    the maximum of 7, and restrict the maximum to 3 for four-port variants
> 
> Changes in v15:
>  - Add compatible strings for the P3H2440, P3H2441, P3H2840 and P3H2841
>    variants
>  - Fix the target-port reg schema to describe the single-cell port index
> 
> Changes in v14:
>  - No change
> 
> Changes in v13:
>  - Fix mismatch between example unit-address and reg property by correcting the reg value
>    to match the node name
> 
> Changes in v12:
>  - No change, added Reviewed-By tag
> 
> Changes in v11:
>  - No change
> 
> Changes in v10:
>  - No change, added Reviewed-By tag
> 
> Changes in v9:
>  - Referenced i3c.yaml and i2c-controller.yaml for child nodes
>  - Dropped unnecessary #address-cells and #size-cells from child nodes
> 
> Changes in v8:
>  - Add compatible in i3c example
> 
> Changes in v7:
>  - Fix schema validation issues
>  - Adjust required properties
>  - Add I2C example
> 
> Changes in v6:
>  - Use a vendor prefix for the attributes
> 
> Changes in v5:
>  - Removed SW properties: cp0-ldo-microvolt,cp1-ldo-microvolt,
>    tp0145-ldo-microvolt, tp2367-ldo-microvolt
>  - Changed supply entries and its descriptions
> 
> Changes in v4:
>  - Fixed DT binding check warning
>  - Removed SW properties: ibi-enable, local-dev, and always-enable
> 
> Changes in v3:
>  - Added MFD (Multi-Function Device) support for I3C hub and on-die regulator
>  - Added Regulator supply node
> 
> Changes in v2:
>  - Fixed DT binding check warning
>  - Revised logic for parsing DTS nodes
> ---
> ---
>  .../devicetree/bindings/i3c/nxp,p3h2840.yaml  | 328 ++++++++++++++++++
>  MAINTAINERS                                   |   9 +
>  2 files changed, 337 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/i3c/nxp,p3h2840.yaml
> 
> diff --git a/Documentation/devicetree/bindings/i3c/nxp,p3h2840.yaml b/Documentation/devicetree/bindings/i3c/nxp,p3h2840.yaml
> new file mode 100644
> index 000000000000..6b0076b4487f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i3c/nxp,p3h2840.yaml
> @@ -0,0 +1,328 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright 2025-2026 NXP
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/i3c/nxp,p3h2840.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: NXP P3H2X4X I3C HUB
> +
> +maintainers:
> +  - Aman Kumar Pandey <aman.kumarpandey@nxp.com>
> +  - Vikash Bansal <vikash.bansal@nxp.com>
> +  - Lakshay Piplani <lakshay.piplani@nxp.com>
> +
> +description: |
> +  P3H2x4x (P3H2440/P3H2441/P3H2840/P3H2841) is a family of multiport I3C
> +  hub devices that connect to:-
> +  1. A host CPU via I3C/I2C/SMBus bus on upstream side and connect to multiple
> +     peripheral devices on the downstream  side.
> +  2. Have two Controller Ports which can support either
> +     I2C/SMBus or I3C buses and connect to a CPU, BMC or SOC.
> +  3. P3H2840/ P3H2841 are 8 port I3C hub with eight Target Ports.
> +  4. P3H2440/ P3H2441 are 4 port I3C hub with four Target Ports.
> +     Target ports can be configured as SMBus or I3C and connect to
> +     peripherals.
> +
> +  All variants use the same register interface. Software reads the number
> +  of target ports from DEV_CAPAB. The x0/x1 variants differ in their
> +  power-up defaults, which the driver replaces with the DT configuration.

I don't understand what this driver reference means and what is its
purpose here.

> +
> +properties:
> +  compatible:
> +    enum:
> +      - nxp,p3h2440
> +      - nxp,p3h2441
> +      - nxp,p3h2840
> +      - nxp,p3h2841

I don't see improvements.


Best regards,
Krzysztof