Re: [RFC 1/2] dt-bindings: clk: versaclock5: Add load capacitance properties

Luca Ceresoli
2021-01-08T22:50:29Z

Hi Adam,

On 06/01/21 18:38, Adam Ford wrote:
> There are two registers which can set the load capacitance for
> XTAL1 and XTAL2. These are optional registers when using an
> external crystal. Update the bindings to support them.
>
> Signed-off-by: Adam Ford <aford173@gmail.com>
> ---
> .../devicetree/bindings/clock/idt,versaclock5.yaml | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> index 2ac1131fd922..e5e55ffb266e 100644
> --- a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> +++ b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> @@ -59,6 +59,18 @@ properties:
> minItems: 1
> maxItems: 2
>
> + idt,xtal1-load-femtofarads:

I wonder whether we should have a common, vendor independent property.
In mainline we have xtal-load-pf (ti,cdce925.txt bindings) which has no
vendor prefix. However I don't know how much common it is to need
different loads for x1 and x2. Any hardware engineer around?

> + $ref: /schemas/types.yaml#/definitions/uint32
> + minimum: 9000
> + maximum: 25000
> + description: Optional loading capacitor for XTAL1

Nit: I think the common wording is "load capacitor", not "loading
capacitor".

--
Luca