linux-kernel - Re: [PATCH v5 01/10] dt-bindings: npu: rockchip,rknn: Add bindings

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Message-ID: <CAL_Jsq+2mvUDWWvtPSryAiCNJP_=1vNRxARxWTS=-O-LTQO3Dg@mail.gmail.com>
Date: Wed, 28 May 2025 08:41:51 -0500
From: Rob Herring <robh@...nel.org>
To: Tomeu Vizoso <tomeu@...euvizoso.net>
Cc: 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>, Jeff Hugo <jeff.hugo@....qualcomm.com>, 
	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
Subject: Re: [PATCH v5 01/10] dt-bindings: npu: rockchip,rknn: Add bindings

On Tue, May 20, 2025 at 5:27 AM Tomeu Vizoso <tomeu@...euvizoso.net> 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)
>
> Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>
> Signed-off-by: Tomeu Vizoso <tomeu@...euvizoso.net>
> ---
>  .../bindings/npu/rockchip,rk3588-rknn-core.yaml    | 147 +++++++++++++++++++++
>  1 file changed, 147 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..9eb426367afcbc03c387d43c4b8250cdd1b9ee86
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml
> @@ -0,0 +1,147 @@
> +# 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, based on NVIDIA's
> +  open source NVDLA IP.
> +
> +  There is to be a node per each core in the NPU. In Rockchip's design there
> +  will be one core that is special and needs to be powered on before any of the
> +  other cores can be used. This special core is called the top core and should
> +  have the compatible string that corresponds to top cores.

Is this really a distinction in the h/w? If you change which core is
the top one in the DT, does it still work?

> +
> +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:
> +    minItems: 2
> +    maxItems: 4
> +
> +  clock-names:
> +    items:
> +      - const: aclk
> +      - const: hclk
> +      - const: npu
> +      - const: pclk
> +    minItems: 2

It is odd that the non-top cores only have bus clocks and no module
clock. But based on the clock names, I'm guessing the aclk/hclk are
not shared, but the npu and pclk are shared. Since you make the top
core probe first, then it will enable the shared clocks and the
non-top cores don't have to worry about them. If so, that is wrong as
it is letting the software design define the bindings.

Rob