linux-kernel - Re: [PATCH v7 06/10] dt-bindings: npu: rockchip,rknn: Add bindings

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Message-ID: <a8c3df16-a460-49bb-ba4e-1a07135d24e5@arm.com>
Date: Tue, 24 Jun 2025 14:27:57 +0100
From: Robin Murphy <robin.murphy@....com>
To: Tomeu Vizoso <tomeu@...euvizoso.net>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Heiko Stuebner <heiko@...ech.de>,
 Oded Gabbay <ogabbay@...nel.org>, Jonathan Corbet <corbet@....net>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Sumit Semwal <sumit.semwal@...aro.org>,
 Christian König <christian.koenig@....com>,
 Sebastian Reichel <sebastian.reichel@...labora.com>,
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>,
 Kever Yang <kever.yang@...k-chips.com>, Daniel Stone <daniel@...ishbar.org>,
 Da Xue <da@...re.computer>, Jeff Hugo <jeff.hugo@....qualcomm.com>
Cc: devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linux-doc@...r.kernel.org,
 linux-media@...r.kernel.org, linaro-mm-sig@...ts.linaro.org,
 Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: Re: [PATCH v7 06/10] dt-bindings: npu: rockchip,rknn: Add bindings

On 2025-06-06 7:28 am, Tomeu Vizoso wrote:
> Add the bindings for the Neural Processing Unit IP from Rockchip.
> 
> v2:
> - Adapt to new node structure (one node per core, each with its own
>    IOMMU)
> - Several misc. fixes from Sebastian Reichel
> 
> v3:
> - Split register block in its constituent subblocks, and only require
>    the ones that the kernel would ever use (Nicolas Frattaroli)
> - Group supplies (Rob Herring)
> - Explain the way in which the top core is special (Rob Herring)
> 
> v4:
> - Change required node name to npu@ (Rob Herring and Krzysztof Kozlowski)
> - Remove unneeded items: (Krzysztof Kozlowski)
> - Fix use of minItems/maxItems (Krzysztof Kozlowski)
> - Add reg-names to list of required properties (Krzysztof Kozlowski)
> - Fix example (Krzysztof Kozlowski)
> 
> v5:
> - Rename file to rockchip,rk3588-rknn-core.yaml (Krzysztof Kozlowski)
> - Streamline compatible property (Krzysztof Kozlowski)
> 
> v6:
> - Remove mention to NVDLA, as the hardware is only incidentally related
>    (Kever Yang)
> - Mark pclk and npu clocks as required by all clocks (Rob Herring)
> 
> v7:
> - Remove allOf section, not needed now that all nodes require 4 clocks
>    (Heiko Stübner)
> 
> Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>
> Signed-off-by: Tomeu Vizoso <tomeu@...euvizoso.net>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> ---
>   .../bindings/npu/rockchip,rk3588-rknn-core.yaml    | 118 +++++++++++++++++++++
>   1 file changed, 118 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml b/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..0588c085a723a34f4fa30a9680ea948d960b092f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml
> @@ -0,0 +1,118 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/npu/rockchip,rk3588-rknn-core.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Neural Processing Unit IP from Rockchip
> +
> +maintainers:
> +  - Tomeu Vizoso <tomeu@...euvizoso.net>
> +
> +description:
> +  Rockchip IP for accelerating inference of neural networks.
> +
> +  There is to be a node per each core in the NPU. In Rockchip's design there
> +  will be one core that is special because it is able to redistribute work to
> +  the other cores by forwarding register writes and sharing data. This special
> +  core is called the top core and should have the compatible string that
> +  corresponds to top cores.

Say a future SoC, for scaling reasons, puts down two or more whole NPUs 
rather than just increasing the number of sub-cores in one? How is a DT 
consumer then going to know which "cores" are associated with which "top 
cores"? I think at the very least they want phandles in one direction or 
the other, but if there is a real functional hierarchy then I'd be 
strongly tempted to have the "core" nodes as children of their "top 
core", particularly since "forwarding register writes" sounds absolutely 
like something which could justify being represented as a "bus" in the 
DT sense.

Thanks,
Robin.

> +
> +properties:
> +  $nodename:
> +    pattern: '^npu@[a-f0-9]+$'
> +
> +  compatible:
> +    enum:
> +      - rockchip,rk3588-rknn-core-top
> +      - rockchip,rk3588-rknn-core
> +
> +  reg:
> +    maxItems: 3
> +
> +  reg-names:
> +    items:
> +      - const: pc
> +      - const: cna
> +      - const: core
> +
> +  clocks:
> +    maxItems: 4
> +
> +  clock-names:
> +    items:
> +      - const: aclk
> +      - const: hclk
> +      - const: npu
> +      - const: pclk
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  iommus:
> +    maxItems: 1
> +
> +  npu-supply: true
> +
> +  power-domains:
> +    maxItems: 1
> +
> +  resets:
> +    maxItems: 2
> +
> +  reset-names:
> +    items:
> +      - const: srst_a
> +      - const: srst_h
> +
> +  sram-supply: true
> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - clocks
> +  - clock-names
> +  - interrupts
> +  - iommus
> +  - power-domains
> +  - resets
> +  - reset-names
> +  - npu-supply
> +  - sram-supply
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/rockchip,rk3588-cru.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/power/rk3588-power.h>
> +    #include <dt-bindings/reset/rockchip,rk3588-cru.h>
> +
> +    bus {
> +      #address-cells = <2>;
> +      #size-cells = <2>;
> +
> +      npu@...b0000 {
> +        compatible = "rockchip,rk3588-rknn-core-top";
> +        reg = <0x0 0xfdab0000 0x0 0x1000>,
> +              <0x0 0xfdab1000 0x0 0x1000>,
> +              <0x0 0xfdab3000 0x0 0x1000>;
> +        reg-names = "pc", "cna", "core";
> +        assigned-clocks = <&scmi_clk SCMI_CLK_NPU>;
> +        assigned-clock-rates = <200000000>;
> +        clocks = <&cru ACLK_NPU0>, <&cru HCLK_NPU0>,
> +                 <&scmi_clk SCMI_CLK_NPU>, <&cru PCLK_NPU_ROOT>;
> +        clock-names = "aclk", "hclk", "npu", "pclk";
> +        interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH 0>;
> +        iommus = <&rknn_mmu_top>;
> +        npu-supply = <&vdd_npu_s0>;
> +        power-domains = <&power RK3588_PD_NPUTOP>;
> +        resets = <&cru SRST_A_RKNN0>, <&cru SRST_H_RKNN0>;
> +        reset-names = "srst_a", "srst_h";
> +        sram-supply = <&vdd_npu_mem_s0>;
> +      };
> +    };
> +...
>