[PATCH 2/3] dt-bindings: usb: mtk-xhci: Allow middle optional clocks to be missing

[Chunfeng Yun]

On Fri, 2022-06-17 at 18:29 -0400, Nícolas F. R. A. Prado wrote:
> The current clock list in the binding doesn't allow for one of the
> optional clocks to be missing and a subsequent clock to be present.
> An
> example where this is an issue is in mt8192.dtsi, which has "sys_ck",
> "ref_ck", "xhci_ck" and would cause dtbs_check warnings.
How about using fixed clock instead to fix the check warning?
Using enum way seems make it more complex.

> 
> Change the clock list in a way that allows the middle optional clocks
> to
> be missing, while still guaranteeing a fixed order. The "ref_ck" is
> kept
> as a const even though it is optional for simplicity, since it is
> present in all current dts files.
> 
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado at collabora.com>
> ---
> 
>  .../devicetree/bindings/usb/mediatek,mtk-xhci.yaml       | 9
> +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/usb/mediatek,mtk-
> xhci.yaml b/Documentation/devicetree/bindings/usb/mediatek,mtk-
> xhci.yaml
> index 63cbc2b62d18..99a1b233ec90 100644
> --- a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> +++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> @@ -80,8 +80,13 @@ properties:
>      items:
>        - const: sys_ck  # required, the following ones are optional
>        - const: ref_ck
> -      - const: mcu_ck
> -      - const: dma_ck
> +      - enum:
> +          - mcu_ck
> +          - dma_ck
> +          - xhci_ck
> +      - enum:
> +          - dma_ck
> +          - xhci_ck
>        - const: xhci_ck
>  
>    assigned-clocks: