Messages in this thread | | | Date | Wed, 12 Apr 2023 16:32:06 +0200 | Subject | Re: [PATCH 1/2] dt-bindings: phy: imx8mq-usb: add phy tuning properties | From | Johannes Zink <> |
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Hi Rob,
On 4/12/23 15:39, Rob Herring wrote: > On Tue, Apr 11, 2023 at 04:22:37PM +0200, Johannes Zink wrote: >> Hi Krzystof, >> >> thank you for your explanations. As I'm still quite new to writing >> bindings, I still have some questions: >> >> On Fri, 2023-04-07 at 11:03 +0200, Krzysztof Kozlowski wrote: >>> On 05/04/2023 14:14, Johannes Zink wrote: >>>> Hi Krysztof, >>>> >>>> thanks for your review, please find my questions below. >>>> >>>> On Wed, 2023-04-05 at 13:51 +0200, Krzysztof Kozlowski wrote: >>>>> [snip] >>>>>> A phandle to the regulator for USB VBUS. >>>>>> >>>>>> + fsl,phy-tx-vref-tune: >>>>>> + description: >>>>>> + HS DC Voltage level adjustment >>>>> >>>>> "Level" in what units? >>>>> >>>> >>>> The datasheet just shows percent, ranging from -6 to +24%, in 2% >>>> increments. What unit would you suggest? >>> >>> percent >>> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml >> >> I am still a bit confused how to use this properly. How can I restrict >> the values to multiples of 2 in order to avoid illegal values? >> >> At the moment the only thing I could come up with is something like >> >> fsl,phy-tx-vref-tune-percent: >> description: | >> Adjusts the high-speed DC level voltage >> $ref: /schemas/types.yaml#/definitions/int32 > > Note that with standard unit suffixes, you don't need a type. > >> minimum: -6 >> maximum: 24 >> default: 0 >> >> Does something like this work? I am not quite sure if I am on the right >> track here, especially as this requires a signed int, of which I have >> not seen many examples so far. > > We'd have to change the type for -percent to signed. That's possible, > but for vendor specific properties there's not much advantage to use > standard units instead of just using the register values directly. >
I don't have any objections to that, this is pretty much what I sent in my v1 patch <20230405112118.1256151-2-j.zink@pengutronix.de>, but Krzysztof requested to change the vendor specific properties to use property-units.
Would something along the lines of the st,trim-hs-current on Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml be acceptable (i.e. use an enum and annotate the meaning of the values in the description)?
I will, nevertheless, try to make the descriptions a bit more verbose in my v2 (wherever the datasheet gives me proper informations), as Krzysztof requested.
Best regards Johannes
> Rob >
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