RE: [PATCH v4 1/3] dt-bindings: iio: adf4371: add refin mode

Miclaus, Antoniu
2025-01-13T11:50:07Z

--
Antoniu Miclăuş

> -----Original Message-----
> From: Krzysztof Kozlowski <krzk@kernel.org>
> Sent: Monday, January 13, 2025 1:24 PM
> To: Nuno Sá <noname.nuno@gmail.com>; Miclaus, Antoniu
> <Antoniu.Miclaus@analog.com>
> Cc: jic23@kernel.org; robh@kernel.org; conor+dt@kernel.org; linux-
> iio@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-pwm@vger.kernel.org
> Subject: Re: [PATCH v4 1/3] dt-bindings: iio: adf4371: add refin mode
>
> [External]
>
> On 13/01/2025 12:17, Nuno Sá wrote:
> > On Mon, 2025-01-13 at 11:21 +0100, Krzysztof Kozlowski wrote:
> >> On 13/01/2025 10:55, Nuno Sá wrote:
> >>> On Mon, 2025-01-13 at 09:37 +0100, Krzysztof Kozlowski wrote:
> >>>> On Thu, Jan 09, 2025 at 03:37:05PM +0200, Antoniu Miclaus wrote:
> >>>>>    clock-names:
> >>>>>      description:
> >>>>> -      Must be "clkin"
> >>>>> -    maxItems: 1
> >>>>> +      Must be "clkin" if the input reference is single ended or "clkin-
> >>>>> diff"
> >>>>> +      if the input reference is differential. By default single ended
> >>>>> input
> >>>>> is
> >>>>> +      applied.
> >>>>> +    enum: [clkin, clkin-diff]
> >>>>> +    default: clkin
> >>>>
> >>>> Which pins are these? I went through adf4371 datasheet and no
> reference
> >>>> on clock inputs like clkin or clkin-diff.
> >>>>
> >>>>
> >>>
> >>> Hmm, I guess we should call this 'refp' and 'refp-n' then (the latter seems
> >>> a
> >>> bit more odd)? Or just 'ref' and 'ref-diff'?
> >>
> >> That mistake was done at the beginning - the "clkin" is just useless
> >> name. It cannot be "clkout" and it cannot be anything else than clk, so
> >> it is 100% redundant.
> >>
> >
> > Oh sure... Makes sense and I forgot that the property is not new...
> >
> >> But looking for pins brought second point - here you claim these are
> >> mutually exclusive while datasheet suggests that both inputs can be
> >> connected. Unless they come from the same source always?
> >>
> >
> > If you have a single ended input then only one pin (the positive one) will be
> > used. If the input signal is differential, then both pins will be used. So they
>
> But the clocks describe input pins, at least in typical case, so that's
> my question: how many clock sources do you have here? One or two?
>
> > are mutually exclusive... You either have single ended or a differential input.
> > And depending on the input type, the limit of the input frequency varies.
>
> Based on this, this is the same clock, so using "diff" is not a property
> of "clocks". Look at other bindings how they encode differential choice
> for some signals - usually bool property, but not always - see other
> adi/admv devices.

This approach that you suggest was implemented in patch series v1 (as boolean) / v3 (as enum).
Based on feedback in v3 received from Jonathan I switched to this. Should I revert it?

> Best regards,
> Krzysztof