Re: [RFC PATCH v6 3/9] dt-bindings: iommu: rockchip: allow the RK3576 NPU MMU clock set

["Diederik de Haas" <diederik@cknow-tech.com>]

On Thu Aug 6, 2026 at 8:34 AM CEST, Jiaxing Hu wrote:
> The RK3576 NPU MMUs need more than aclk and iface. With only those two
> enabled the MMU accepts reads but silently drops register writes: a
> DTE_ADDR value written from the power domain, while the domain clocks
> are still on, reads back correctly, and the write rk_iommu_resume() does
> microseconds later does not land at all. The vendor DT names the CBUF
> clocks as that MMU's interface clocks and its driver keeps every NPU
> clock on for as long as the device is powered.
>
> The driver side of this is already upstream, commit 841363ebb508
> ("iommu/rockchip: Take all DT clocks"), which switched rk_iommu to
> devm_clk_bulk_get_all(). Widen the schema to match so those nodes can
> be described. minItems stays at 2, so every existing devicetree, which
> all carry exactly aclk and iface, is unaffected.

I agree with all remarks Sashiko made wrt this patch:
https://sashiko.dev/#/patchset/20260805063826.95682-1-gahing%40gahingwoo.com?part=3

Now every MMU with "rockchip,rk3568-iommu", "rockchip,rk3588-iommu" or
"rockchip,rk3576-iommu" is allowed to have a minimum of 2 clocks, instead
of having exactly 2 clocks. That does not sound desirable.

Cheers,
  Diederik
>
> Signed-off-by: Jiaxing Hu <gahing@gahingwoo.com>
> ---
>  .../devicetree/bindings/iommu/rockchip,iommu.yaml         | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/iommu/rockchip,iommu.yaml b/Documentation/devicetree/bindings/iommu/rockchip,iommu.yaml
> index 6ce41d11f..a3cedcaaa 100644
> --- a/Documentation/devicetree/bindings/iommu/rockchip,iommu.yaml
> +++ b/Documentation/devicetree/bindings/iommu/rockchip,iommu.yaml
> @@ -42,14 +42,22 @@ properties:
>      minItems: 1
>  
>    clocks:
> +    minItems: 2
>      items:
>        - description: Core clock
>        - description: Interface clock
> +      - description: Compute clock, RK3576 NPU MMUs only
> +      - description: Convolution buffer core clock, RK3576 NPU MMUs only
> +      - description: Convolution buffer interface clock, RK3576 NPU MMUs only
>  
>    clock-names:
> +    minItems: 2
>      items:
>        - const: aclk
>        - const: iface
> +      - const: npu
> +      - const: aclk_cbuf
> +      - const: hclk_cbuf
>  
>    "#iommu-cells":
>      const: 0