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SubjectRe: [PATCH 2/3] dt-bindings: usb: mtk-xhci: Allow middle optional clocks to be missing
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On Fri, 2022-06-17 at 18:25 -0700, Krzysztof Kozlowski wrote:
> On 17/06/2022 15:29, 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.
> >
> > 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@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
>
> You allow now almost any order here, including incorrect like
> sys,ref,xhci,xhci,xhci.
>
> The order of clocks has to be fixed and we cannot allow flexibility.
> Are
> you sure that these clocks are actually optional (not wired to the
> device)?
In fact, these optional clocks are fixed, due to no gates are provided,
SW can't control them by CCF;
In this case, I usually use a fixed clock, or ignore it.

>
>
> Best regards,
> Krzysztof

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