Re: [PATCH net-next v4 01/14] dt-bindings: net: Add PPE for Qualcomm IPQ9574 SoC

[Krzysztof Kozlowski]

On Tue, May 13, 2025 at 05:58:21PM GMT, Luo Jie wrote:
> The PPE (packet process engine) hardware block is available in Qualcomm
> IPQ chipsets that support PPE architecture, such as IPQ9574. The PPE in
> the IPQ9574 SoC includes six ethernet ports (6 GMAC and 6 XGMAC), which
> are used to connect with external PHY devices by PCS. It includes an L2
> switch function for bridging packets among the 6 ethernet ports and the
> CPU port. The CPU port enables packet transfer between the ethernet
> ports and the ARM cores in the SoC, using the ethernet DMA.
> 
> The PPE also includes packet processing offload capabilities for various
> networking functions such as route and bridge flows, VLANs, different
> tunnel protocols and VPN.
> 
> Signed-off-by: Luo Jie <quic_luoj@xxxxxxxxxxx>
> ---
>  .../devicetree/bindings/net/qcom,ipq9574-ppe.yaml  | 406 +++++++++++++++++++++
>  1 file changed, 406 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/qcom,ipq9574-ppe.yaml b/Documentation/devicetree/bindings/net/qcom,ipq9574-ppe.yaml
> new file mode 100644
> index 000000000000..f36f4d180674
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/qcom,ipq9574-ppe.yaml
> @@ -0,0 +1,406 @@
> +# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/net/qcom,ipq9574-ppe.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm IPQ packet process engine (PPE)
> +
> +maintainers:
> +  - Luo Jie <quic_luoj@xxxxxxxxxxx>
> +  - Lei Wei <quic_leiwei@xxxxxxxxxxx>
> +  - Suruchi Agarwal <quic_suruchia@xxxxxxxxxxx>
> +  - Pavithra R <quic_pavir@xxxxxxxxxxx>>

Double >>

> +
> +description:

You got here comment didn't you?

> +  The Ethernet functionality in the PPE (Packet Process Engine) is comprised
> +  of three components, the switch core, port wrapper and Ethernet DMA.
> +
> +  The Switch core in the IPQ9574 PPE has maximum of 6 front panel ports and
> +  two FIFO interfaces. One of the two FIFO interfaces is used for Ethernet
> +  port to host CPU communication using Ethernet DMA. The other is used
> +  communicating to the EIP engine which is used for IPsec offload. On the
> +  IPQ9574, the PPE includes 6 GMAC/XGMACs that can be connected with external
> +  Ethernet PHY. Switch core also includes BM (Buffer Management), QM (Queue
> +  Management) and SCH (Scheduler) modules for supporting the packet processing.

...

> +  clock-names:
> +    items:
> +      - const: ppe
> +      - const: apb
> +      - const: ipe
> +      - const: btq
> +
> +  resets:
> +    maxItems: 1
> +    description: PPE reset, which is necessary before configuring PPE hardware
> +
> +  interconnects:
> +    items:
> +      - description: Clock path leading to PPE switch core function
> +      - description: Clock path leading to PPE register access
> +      - description: Clock path leading to QoS generation
> +      - description: Clock path leading to timeout reference
> +      - description: Clock path leading to NSS NOC from memory NOC
> +      - description: Clock path leading to memory NOC from NSS NOC
> +      - description: Clock path leading to enhanced memory NOC from NSS NOC
> +
> +  interconnect-names:
> +    items:
> +      - const: ppe
> +      - const: ppe_cfg
> +      - const: qos_gen
> +      - const: timeout_ref
> +      - const: nssnoc_memnoc
> +      - const: memnoc_nssnoc
> +      - const: memnoc_nssnoc_1
> +
> +  ethernet-dma:

I don't get why this is a separate node.

> +    type: object
> +    additionalProperties: false
> +    description:
> +      EDMA (Ethernet DMA) is used to transmit packets between PPE and ARM
> +      host CPU. There are 32 TX descriptor rings, 32 TX completion rings,
> +      24 RX descriptor rings and 8 RX fill rings supported.
> +
> +    properties:
> +      clocks:
> +        items:
> +          - description: EDMA system clock from NSS Clock Controller
> +          - description: EDMA APB (Advanced Peripheral Bus) clock from
> +              NSS Clock Controller
> +
> +      clock-names:
> +        items:
> +          - const: sys
> +          - const: apb
> +
> +      resets:
> +        maxItems: 1
> +        description: EDMA reset from NSS clock controller
> +
> +      interrupts:
> +        minItems: 29
> +        maxItems: 57

Why is this flexible on the same SoC?

Best regards,
Krzysztof